Considering an '84 190 D 2.2 (201.122; OM601.921)with 107K miles as a possible acquisition from an estate. Service hx and prior owner are unavailable. Vehicle has remained unused for over a year. Transmission fluid is clean but with the engine off the fluid level was substantially above the dipstick's max level; Bowden cable is properly connected to throttle linkage; cable moves freely and appears to be intact.

Installed new battery, renewed fuel filter; engine started immediately. After warmup, rechecked/corrected trans fluid level (down 1.5 qts) but... only reverse and first gears are functional, no upshifting is occurring in automatic or manual shifting mode. Both gears engage cleanly, with no slippage and engine speed moves to redline when given fuel, with a commensurate increase in the vehicle's speed. Just no upshifting.

Any suggestions as to the nature of the problem? Possible solutions?

Thanks in advance.

The first thing that should be checked is the governer pressure. It must be present to create an upshift. If there is no governer pressure (the low measuring point is 30km/H), it's likely that the drive gears for governer and secondary pump have a problem. I'll save the long answer on that for another post.
Dan Haner