Are you interested in adjusting it yourself? Do you have a vacuum gauge?
If not, I agree with the above comments about finding a pro. One who has been working on MB since your car was made would be nice. The vacuum system used on your car was unique to 80-83 240Ds and 80-81 300Ds. It was mostly unique in that it doesn't have a control pressure link. Adjusting the system is almost an art. A tranny shop wouldn't be likely to know a thing about the vacuum system let alone how to finesse it.
Bosch Master, ASE Master, L1
33 years MB technician