88 80Q Locking differential randomly

["Brian Link" <bflink@ouray.cudenver.edu>]

	I am writing in hopes that someone can help with this weird Audi problem. 
I searched the archives and didn't find much.  My friend has a 88 80 Q and
the differential locks at random times.  Sometimes when she starts the car
other times when she stops for a light.  She says she can't unlock it with
the button rather drives up to speed to disengage it.  Usually it goes off
at 15 mph but can take as much as 30 mph to disengage.  A few months ago it
worked perfect....Any advice would be much appreciated.

thanks
Brian Link
Boulder, CO

P.S.  I told her about the list so maybe her and her other female Audi
owning friend will join to improve the m/f ratio.