A1200 internal floppy drive weird happenings

[Tricky]

I've started getting this strange problem with my internal disk drive.  Sometimes I finish a disk operation, and then take the disk out WAY after it's finished accessing and the light's gone out, and suddenly it starts trying to access the disk and demands it back again!  Well that was the first thing that started to happen.  It's lately also progressed to randomly trying to read disks when none have been inserted at all.

I'm guessing this is a problem with the little switch inside that detects whether a disk has been inserted or removed, sending erroneous signals.  Does anyone have any ideas how to fix it, or do I have to invest in a replacement floppy drive?

[Tricky]

I noticed that.  It does seem to go away.  I'll get me some switch cleaner or something.  Failing that...

We managed to replace my b/f's A1200 drive with one out of an old bust A500.  One of the 2 A500 drives we got was too tall to fit!  The other one had extra metal bits screwed on to raise it to the correct height, but without them it was too low and the motor scraped against the metal shielding underneath, so I had to put some card underneath to raise it ip (there's no bottom panel on the drive).  But it works, although strangely the drive light doesn't come on.