Defective power adapter??

Question

My iBook gave me quite the scare last night. (I'm using my Compaq Presario (w/ Vista, God help me!) to post this.)
My iBook had about 20 percent left on the battery, so I put it to sleep and plugged it in to charge it. About an hour or so later, I checked and the battery had drained to 18 percent. The plug light was amber, but it obviously wasn't charging. And here's what was flakey: There was a soft buzzing sound from the power adapter. When I shut down the iBook, the buzzing stopped and the light stayed amber. But I checked another hour later and the battery continued to slowly drain.
So, I checked these discussion boards, reset the PMU, took out the battery and put it back in, checked the power at about this mac (it was not charging and the battery had -- I can't remember exactly -- zero capacity), tried the power adapter with the 2-prong thing (without the three-prong extention), and the battery continued to drain. It finally got to the point where the iBook would go to sleep in less than a minute. I could barely power up or shut down. The iBook did nothing when I tried only the power adapter with the battery removed.
So I'm thinking do I need to replace the adapter, the logic board, the DC in board, the battery?? Then I again unplugged the power plug and checked the pin for damage. There isn't any. I plugged it in again and booted, and now IT'S CHARGING. And the About this Mac > power shows a healthy, charging battery. I shut down, and it's charging now, no buzzing noise, and I'm not touching it until the light is green.
Can somebody tell me what happened? Do I need a new power adapter? I bought this iBook new from Apple in September 2005. It has the orignial battery. I've never had any real problems with my iBook. What's going on?

Answer 1

Just an update, but I'm hoping that this problem is solved.
The new battery I ordered from OWC arrived today. I replaced the original battery and NO PROBLEM. I didn't have to wiggle the plug or anything. Everything is working as it should. The battery has charged 100 percent and I'm keeping the plug in for 12-plus hours, as instructed to calibrate it.
I'll know for sure if that was the problem after I drain the new battery to empty and see if it recharges as it should. But for now it looks like the 29 month old original battery was the problem. That kind of ticks me off because it still had 56 percent of its original capacity. It seems like I should have gotten another year of use out of it. When I removed it (and it was fully charged), it had 484 load cycles.
The battery from OWC ($99) was a lot cheaper than Apple's price ($129). Also, they were not overly helpful at the closest Apple store (23 miles away). I would have to bring the iBook in so they could inspect it. They would have to order the part (if it was the DC-in board) and I would have to make a second trip to the store. The part wasn't in, but even if it was, they wouldn't hold it for me, and they wouldn't order it for me until they inspected the iBook, and they wouldn't just sell me the part. I had to have it installed by them for $85. The DC-in board is $12. The cheapest new one I could find on line was $29.95 (and $9 shipping).
So ... I'm hoping the new battery fixed everything. All seems to be well.