1979 116 diesel transmission

[DaveMcDonald]

Thought I might gain insight here. I have a '79 116 chassis turbo diesel. It wont shift out of 1st gear until about 3500 rpms. I adjusted the modulator all the way out, but it hasnt helped. The modulator holds good vacuum. Can a modulator be faulty even if it holds vacuum, or am I dealing with a sticky valve in the valve body?I havent had the car very long , but I know that it sat for a period of time. Anyone have any insight/knowledge of these 4 bolt pan trannys? Any direction would be appreciated. Thanks Dave