X220 complete fan failure

Question

I've had my X220 for about a year now. At first, I didn't experience any problems with the fan, no revving up/down like some describe, and it was pretty quiet.
After about 9 months of usage, the fan started to get pretty noisy. As I also usually have a room fan always on, I didn't care much because the room fan overpowered the laptop fan.
Then, at about 10 months ago, one fine day CoreTemp pops up a message that my CPU temp is critical, I was just watching a movie with no background stuff going on. I've checked TPFanControl and the fan wasn't running. It was also not responding to TPFanControl's smart or manual modes.
I turned off the laptop, removed the keyboard and powered it on again. The fan would spin a few revs at pretty low speed, then just stop. I allowed the system to boot like that, and tried to start the fan with TPFanControl's manual mode. When I switched the fan from speed 0 to any other speed, I could see the fan blades to move just a little bit (maybe 1mm) and then stop again.
The laptop is on warranty, but I bought it in USA, and I live in Thailand now. Also this is my primary work computer and I didn't want any unnecessary downtime, so I decided to fix it myself.
I wrote quite a lot, those not interested in the disassembly story, just skip the next paragraph.
Well, luckily I decided not to sell my old Z61m, I booted it up to view the X220 Hardware Maintenance Manual: http://download.lenovo.com/ibmdl/pub/pc/pccbbs/mob​iles_pdf/x220_x220i_hmm_0a60739_06.pdf
Using an old laptop, which one year ago didn't feel slow, after being accustomed to the new one, was really sluggish. Part of the reason might be that I recently installed Windows 7 on it (it's got 4Gb RAM in it, of which the chipset can only use 3Gb). By the way, one time I had my Z61m's fan become really noisy, too (but never fail completely), I did disassemble, clean and oil the fan - and getting to the fan was much easier than on X220.
On X220 to get to the underside of the fan, you have to remove the motherboard, the heatsink assembly is screwed to the motherboard from it's underside. That's wasn't hard for me, but I could easily see messing up some small component. To remove the motherboard, I had to remove the HDD, speakers, bluetooth module, WiFi module, mSATA SSD, disconnect a few flat-ribbon connectors, unclip a few regular connectors, free the wifi antenna cables, video cable from their grooves in the bezel, remove the bezel. And then the motherboad still wouldn't come off - the two nuts holding the VGA connector have to be removed. And when I moved to Thailand, I didn't bring my 5mm hex socket with me. So I had to drive around (I live in a small city), trying to find it. Tool shops, hardware shops, computer shops didn't have it! Well, a tool shop had a huge kit of 1/4" DR tools, I wasn't gonna spend so much money just to get one 5mm socket. In the end I could find a low quality 1/4" DR sockets set in a Tesco supermarket, for $2. But  what do you know? The cheap sockets have thick walls, so the wall thickness doesn't allow it to fit around the nut (the laptop's case is in the way). Too bad I don't have a lathe... well here comes the drill to hold the socket and the angle grinder. Finally I was able to unscrew the nuts and take out the motherboard.
To get out the audio connector from it's hole in the case, I have to flex the motherboard quite a lot, I know it's fiberglass and strong, but it does feel quite scary (the narrowest part of the mainboard is just maybe an inch wide).
I then tilted the motherboard up disconnected the power cable (it's a bit tricky, but I think it's the most efficient way - some say to remove the LCD to do that! that's totally unnecessary), took the motherboard out and unscrewed the heatsink/fan assembly.
The fan would turn by hand or by blowing air into it, but wouldn't keep rotating as soon as I stop blowing. The blades are fortunately removable (just grab them and pull), I cleaned them and the insides with some methyl alcohol, let it dry, then put some TriFlow teflon oil in there and put the blades back on. I then put everything back together, and it worked fine. Assembly, as usual, is the reverse of disassembly. The fan works, and is pretty quiet again (I'd say about the same as it was new).
The fan is sleeve bearing. I think it's not a good practice to put sleeve bearing fans into laptops. When a ball bearing fan fails, it just rotates at reduced speed, with plenty of noise and vibration. Giving a lot of warning time that it should be replaced. A sleeve bearing fan can just stop turning completely, not making any noise to indicate failure. It's very fortunate that CPUs (and some other hardware) have automatic overheat protection (thermal throttling). I suppose Lenovo just had some temporary problem sourcing the necessary qty of ball bearing fans when they were producing X220, so they just put in an alternative they could find. I don't think they did this just to save $1 per laptop. In any case, my advices for X220 owners is, if your fan has become noisier than before, open it up and clean/oil it, better now than later. I would only advise this job to people who have straight hands growing from the right place, not from their ass (that's a saying we have in Russia). There is nothing really difficult about this job (first time will take 2-3 hours, with experience you can do the whole job in under 1 hour), but you have to be careful. There are a lot of small parts that can be dropped or damaged by static electricity. There are many screws of different sizes that can be mixed up (my advise is to use a small container with multiple compartments, and put the screws into different compartments, along with a piece of paper saying where does this group of screws go. Have to be very careful disconnecting the connectors, especially the flat ribbon type. No sharp or metal tools should be used for this task! Use only fingernails or something plastic. Also use care to properly align the flat ribbon cables when connecting (locking) them. It's good to take pictures of the whole process, especially things like cable routing. You'll thank yourself for this when putting it back together. The hardware maintenance manual is also pretty useful (might be not so easy to find the right info, though, have to read carefully). Print it or use another computer or a mobile device to access it when doing the job. As noted, you will need a 5mm thin-wall socket (any good quality 1/4" DR socket will be thin wall, while cheap nasty stuff will be thick wall) to unscrew the VGA connector. The nuts are not tight from the factory (at least mine were not), so you might be able to use another tool, but I think even the smallest needle-nose pliers won't fit there, there's really too little room between the nuts and the case. A sturdy tweezers with round ends (or cut off ends) might do the job, but I'm a believer in using a proper tool for a job, at least when talking about a $1000 computer (this is not very Russian of me, where a common tool for automotive repair is often a hammer and a block of wood; a saying goes: if you fail - use a bigger hammer). Obviously you also need a small-size electronics screwdriver.
A thing I had a problem with: the heatsink contacts both CPU and the chipset (which is common in notebooks), there was thermal compound on the CPU and a thermal pad on the chipset (I would say 0.5mm thick). Unfortunately I tore up the pad when removing the heatsink. If you're careful, usually you can reuse the pad. The pad is there for the reason that the CPU and the chipset surfaces are not on the same plane, so if assembled with just a super-thin layer of thermal compound (like you're supposed to for optimal heat conduction), the chipset wouldn't touch the heatsink and would overheat. Since I didn't have a spare thermal pad on hand, I used a thick layer of thermal compound (I used Arctic Silver 5, which is pretty thick consistency and not very likely to flow out of there) on the chipset. I also ordered some thermal pads on eBay, to have it just in case.
I haven't noticed any significant decrease in temperatures with the new thermal compound, even after 200 engine hours the AS5 needs for optimal performance. It might be cooler by a couple of degrees, but not by much.
I'm sorry I deleted the pics I took during disassembly.
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Answer 1

A .5mm layer of thermal paste will not do a very good job of heat conduction. There will be air bubbles. No matter how well you spread out the thermal paste on the CPU die, you will never get the kind of even, thin layer that you get with a new fan, which comes with lots of little dots. BTW, very small needle-nosed pliers work fine to start the VGA nuts. The first time I take a particular model apart, I tape the screws near the place the will go back using "painter's masking tape", which leaves no adhesive residue.