W-124 Transmission

[Mino Erhan]

Hello,
I have 86 300E. 172K.

Symptoms:
Transmission is acting like its slipping. It is up-shifting quicker than it used to. I can not hold it in gear longer. Only when I have full throttle form a stop, I am ble to hold the gear with any length. It seems when I drive off from a red light, by the time I reach 25-30 mph, I am in fourth.

It also downshifts harder than it used to, when you come to a stop. I can definetly feel it engaging to 3rd and than 2nd.

Kick down works only when fully depressed for a long time, and doesnt seem to work at higher rpm. Around 2500-3000rpm.

Maintenance:
Changed transmission filter and fluid 10K ago. Also cable is attached according to manual, with no tension at stop. Kick down solenoid and switch check fine. New vacuum line.

Question:
When I bought the car, the MB Dealership had done a "transmission adjustment". I do not understand what that means. I am not sure they know either. They say "R&R the Valve body and cleaned reverse lock piston, adjusted transmission" Do these transmissions have internal adjsutments?

Please help me out. Do I need a new transmission or can I get it serviced. Or do I need adjustment. Help!!

Thank you