[hogweed]

OK, another update after a further 3 or 4 hours fiddling… I sprayed contact cleaner in the holes, as Stocktake suggested, gave it a spin – another spray etc. But trying to stop the little worm on the motor spindle from rotating when current is applied, it does feel pretty strong anyway.


Anyway, left it overnight to do its work, and tried again today – no joy. I then began an endless sequence of cleaning, re-greasing, and trying different combinations of old and new gears (the old ones look OK to my untutored eye, but the trouble is, you can’t see what’s happening when the case is assembled).


If I put the horizontal spindle (which meshes directly with the motor) in place, leave out the vertical spindle, and bolt the lid down, it whirrs away happily. The problem is when I include the vertical one – and there may be more than one problem. The fact is, it doesn't seem to fit well in the lower hole in the new casing, and is tight to turn. So I very gently reamed the hole out by sliding a slightly smaller drill bit up and down, re-greasing, and trying the spindle again, till it felt like it was turning freely.


Put it all back together – nope. Endless iterations and combinations ensued – eventually I found one which seemed to work. This consisted of using the original old vertical spindle with the new horizontal one (new case and cap also).


The motor dutifully rotated its ¼ turn back and forth, back and forth. I nearly threw a party. Reassembled it in the rest of the mirror mechanism, and… nothing but clicks. Took the motor off again, and on a whim, slightly loosened the Torx screws which hold the cap on… it started working again.


What all this suggests to me is that the gears and the new casing don’t quite match. I’m guessing – no more than that – that the vertical spindle is a tiny fraction of a millimetre too long, and jams when the lid is fully tightened, but really, *!@? knows.


With the lid screws left maybe ¼ of a turn loose, and the mirror reassembled and connected to the car, it graunches and grinds a bit of the way in each direction, then stops. This is just like it did before I started this sorry project.


Only worse.