The 3-2 valve on the valve cover leaked on my 1980 and was
the cause of all my shifting problems.

It is easy to test with a vacuum pump (mitey-vac type).

I can't be sure from what you wrote that the valve was tested.

The small arm on the valve can be replaced separately from the whole valve.

On these particular years, that valve has to be operational.

Was the shop that did this work a Mercedes oriented shop ?
Vacuum is crucial to the operation of a Diesel Mercedes.

Not everybody gets that.

In addition , I had to carefully arrange the vacuum connections to
feed trans, heat/ac system, door locks, and shutoff.

For me on my old car arranging them in the wrong way on the tees
had adverse effects.

With a vacuum pump , do some isolated testing of each part and see
what you get.

__________________
80 300D 340K Owned 30 yrs
83 300SD 440K Owned 9 yrs - Daily Driver 150mi/day
02 Z71 Suburban 117,000
15 Toyota Prius 2600 miles
00 Harley Sportster 24k
09 Yamaha R6
03 Ninja 250