I second what Evan said.  The valve body is an interesting hydraulic
analog computer which controls the shift points by balancing the demands
from your foot (throttle pressure) against the speed info from the
governor.  You just need to be very organized and clean when operating
on it.  There are lots of parts.
  The governor is another of the usual suspects; you should pull it out
and check that the weights and springs operate freely and especially
that the passages are not plugged with lint or gunk.
    On the other hand, I have had very good results using Seafoam AT
flush on a J**p Ch*rokee.
Good luck,

Larry A.

Mark Erb wrote:

> 1988 Westfalia with 95,000 miles, AT fluid changed 25,000 miles ago.
> AT fluid is at the proper level. No AT fluid in the coolant. The
> problem that has cropped up is the transmission sometimes does not
> want to shift into 3rd gear and will wind out until I let off the gas
> for a bit then it will slip into 3rd. The reverse gear will sometimes
> not engage right away then will go into reverse with a big clunk.
> These problems don't always occur but will happen even with a hot and
> cold engine. Anyone else have this problem? Thoughts? A solution
> perhaps? I have easy access to transmission shops (AAMCO, Cottman,
> even a shop that does german transaxles) but I wanted to at least
> have some ideas before I discuss options with a shop or try to tackle
> it myself. Thanks for any feedback. Mark
>