Window grinding noise

[AW <weststar@ziplink.net>]

I just replaced the carrier/cylinder/locking ring on the driver's door
lock for my 1990 80Q.  The lock now works fine, but the window makes a
funny sound.  Going down, the window travels smoothly and sounds fine.
Going up the window moves fine, but I hear a grinding sound.  Before I
go back into a very cold garage to pull the door apart again, can anyone
suggest where to look for the problem?
TIA for any help.
Andy
'92 S4
'90 80Q