Hollow Thumping noise while turning in '92 100s

[mark <mconnor@frontiernet.net>]

I am hoping that someone out in Audiland can shed some light on this
problem.  I have a '92 100s and am experiencing an annoying thump in the
front end drivers side when turning.  I have checked the tie rod ends
and rubber bushings and as as near as I can tell all are good.  I have
found while parked, if I turn the wheel till I hear the thump I can then
repeatedly recreate the thumping noise by simply rocking the steering
wheel back and forth slightly.  It acts like something is catching in
the strut or the shock tower and as the wheel turns the stored energy is
then released (kinda like a coiled spring).  Is there any
idiosynchracies about the struts that I am missing?  I have removed the
plastic cap on the top of strut to observe any movement;  there doesn't
appear to be any, everything appears tight.  Was wondering if the bottom
of the strut cartridge or the bottom pin that connects to the strut are
causing my problem. Perhaps the struts were improperly installed by the
previous owner?  Any thoughts or suggestions would be greatly
appreciated!  Thanks in advance.

Regards
Mark