There are two sliding windows on my vanagon.  They can't easily get
popped out of their track because of a plastic spacer that keeps it
tightly into its frame/track.  So what do you do when said plastic
spacer gets old and crumbles away and needs to be replaced?  I've done
some looking around, but know one seems to know how to get a
replacement.  Surely someone else on the list has had this problem.
I've done some looking around at my local parts junkyard and other
sliding windows there suffer from the same problem.  I suppose I could
Gerry-rig something, but I'm not particularly good at that sort of
thing.

Thanks for your help.