Here is an order of things that should be replaced...

Aux water pump, may be able to clean/grease old one...FUSE..it
Amplifier behind glove box liner
Foam Sensor tube behind glove box...

This should cause it to work...unless...you have vacuum leaks or bad vacuum pods..

Now I would not get a used servo at a junk yard unless it is the newer aluminum bodied unit. The same goes with the amplifier...If your lucky you may find one with a new servo and amp....these servos were only used on 1976-1978 cars...minus 240D's and euros..

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