Your description parallels an experience I had with my 89 Westy. I nearly
wrecked my shoulder after driving over 1,000 miles with this sticky shift
problem.

Someone suggested I may have a shift linkage problem. I was able to fully
correct the problem by following the advice in a repair manual.

If you have access to Haynes' "VW Transporter", you can find a good
description of how to fix the shift linkage on page 7A-3. If you do not
have the book and want these instructions, get back to me and I will copy
and send the instructions.

I did the repair alone but it's easier with a second person to make the
awkward, but not difficult, adjustments necessary.

Dan in Madison
89 Westy 4 speed