I was the source of one of those threads you mentioned.   I did obtain a
motor from a scrappie but it was the wrong one.   It appears that there are
two initial types, one for cars with climate control and one for those (like
mine) without.    I now know that the latter divides into two more motors,
those fitted up to mid 1999 and those after.   I assume the same may be true
of the other type.   The motor I got was the later one so I returned it and,
at present, I am running without the motor fitted.  Obviously I have to have
the vent flap permanently open but, apart from the odd occasion when you are
following a smelly exhaust it is fine (and decidedly cheaper).

The only thing that concerned me about getting replacement gears was that I
did not know why they stripped in the first place.   There is an electronic
component in the unit which I suspect may be to detect increased load (i.e.
when the flap reaches the end of its travel) and shut off the power.   If
that is its function then it could well be that new gears would strip pretty
quickly.

Maybe one of the experienced guys on the group can confirm whether that is
the case.

Buccaneer (formerly Keith Willcocks)