Groaning (then non-working) electric windows

["amz" <amz@eskimo.com>]

I think the passenger-side front window (motor?) in my 88 5ksq has died some
sort of a painful death.  It began about a week ago when the window would
sometimes groan slightly when closed.  No problems opening.  Yesterday, it
started to groan as it went up and the window stopped, but it seemed like
the motor was still going for a little while.  To make sure the motor was in
the 'down' position, I then opened the window.  It now didn't like doing
that, either.  I then closed the window by helping the glass along.  It
stays closed.

Is it possible that the motor or other parts are generic or at least
available in GM 'flavor' like the seats & A/C?

Is it possible that the motor still works, but that the glass slid out of a
track or off of some arm and that's what caused the groaning?

A non-Audi mechanic friend is willing to take a look at it and I'd like to
pass on any tips or info you can suggest.

Thank you in advance for any assistance you can provide.