Thank you Tim and Don for the info on the Diff lock. Haven't had much of
a chance to crawl around underneath the van. I do know that that the
switch to the servo is ok, or appears so. Pulled the dash switch and
then popped off the white vacum line by the servo and got a hissing. The
screws and bracket are pretty rusty, so a bit of penetrating fluid for a
few days should help loosen things up.
Thanks once again.

R Feueriegel
88 syncro