IPad, iCal and iTunes sync problem

Question

Early last year, I posted (https://discussions.apple.com/message/18503738#18503738) that syncing between my iPad 3 and my Snow Leopard iMac behaved oddly.  AppleCare Support dweebs had failed to resolve the issue and no one on here managed to come up with any suggested fix.
However, for no apparent reason, the problem stopped and I stopped monitoring this august and highly esteemed forum and all went well ...
... until recently.
I sync via a USB cable and I do not use iCloud (as I'm on Snow Leopard) save for Find My iPad, all other iCloud options are switched off.  All other app syncing appears to work correctly, it is only iCal and Calendars that don't.
Just why things have started to go wrong now, probably in the last three or four weeks, I do not know but now the following syncing errors occur ...
1) On the iPad: new appointments or changes to appointments made on the iPad are not synced to the iMac;
2) On the iMac, changes to appointments already on the iMac are shown on the iPad as both the new and old timings/details, not as replacements;
3) On the iMac, new appointments are made in the default (or last) calendar used.  These are then edited as required, with the details put in and, if necessary, calendars changed.  On the iPad, however, these will show as both "New event" in the default calendar and as the edited correct appointment, not just as the finalised entry;
4) Appointments deleted from the iMac are not deleted from the iPad.
In other words, changes on the iPad are not synced across to the iMac and changes on the iMac are synced twice, once as the unedited appointment and once as the edited appointment - if an appointment is deleted it remains on the iPad.
When the original problem arose (similar but not identical) the Apple dweebs suggested deleting my iCloud account (not synced, used only for Find My iPad) but doing that this time does not remove the bug.
I'm running a 27" quad-core i7 iMac under MacOSX.6.8 (Build 10K549), iCal v4.0.4 (1395.7) and I sync via USB  and iTunes v11.0.2 (26).  The iPad is a 64GB 4G/wifi iPad 3, currently running under under iOS6.1.3.  To the best of my knowledge, all available updates have been applied to both devices.
I have deleted all calendars off the iPad by deselecting Calendars in iTunes' iPad tab, turned it off.  Swicthed off the iMac, Safe Booted and run OnyX full suite, I have then Single User booted, run fsck -fy three times then run applejack AUTO restart, then rebooted the iMac, rebooted the iPad, sync'd without Calendars then resynced with the Calendars selected again.
I had hoped that this would remove any cache files, temporary files, stuck RAM or whatever else could conceivably be causing this bizarre behaviour - to no bl**dy avail!  It is behaving exactly and frustratingly as before!
What on earth is going on?  if I can't use my iPad as my main calendar and add new appointments when out and about and have them synced properly and reliably to my iMac then the whole thing is a waste of time andI shall have to revert to a paper diary again!
HELP!!!!! Please, before I go mad with frustration!

Answer 1

I'm not sure whether getting no replies to this (or the earlier) query is something of which to be proud - or terrified!
Am I the only person in the world with this bizarre insoluble problem?  if so, why me?  Am I a Chosen One or, more likely, someone to be punished for a lifetime of misdeeds!
But there is progress.  I have no idea what happened at a technical level or why, but the matter has now resolved itself and things are syncing normally.  Until the next time!
Perhaps there is a clue somewhere in the following ...
I run my iMac 24/7 and thus I rarely close iCal on the iMac and when i do it is usually by accident.  The same applies to Calendars on the iPad, although I do reboot from time to time.
Anyway, I installed some software on the iMac which required a reboot and, as susual, iCal opened via Preferences > Accounts > Startup items - only this time I was presented with a perfectly blank calendar.  A message appeared, from within iCal (oh, how I wish i had noticed what it actually said) saying something along the lines of "importing calendars".  This took a little while and it wasn't instant - maybe it does this every time it reatrts but too fast for me to notice.
After this "import", if indeed that's what it was, the syncing was corrected!
Coincidence?  Cause and effect?  Magic?  Too many magic mushrooms for breakfast?
If that is what resolved the issue, then how can I cause an import deliberately for when the syncing goes astray again and just what does an "import" do that a normal launch doesn't and which might have resolved the glitch?
I have had this "import" message before, but very very rarely, so it may well have resolved the syncing issue last time and I just didn't make the possible connection.
Does that help anyone come to my rexcue with an explanation and, possibly, a strategy for preventing or deliberatly correcting syncing issues in the future?