1972 Beetle Auto Clutch will not go into gear while running

Hi, I am trying to help out my neighbor with his beetle. I tested the wire right at the shifter and it gets battery voltage when pulled back and none when released. I assume that is working properly.

I then investigated further to find a diaphragm on the transmission with a bad vacuum line. After replacing it the transmission will still not work when running.

What should I check and how does this auto clutch work?

Is there anyone one here that has worked on they old bugs before

I applied vacuum to the diaphragm and the clutch works and the car goes into gear while running. The engine has vacuum while running. The solenoid has power so I think that it has an internal problem. I am having trouble finding this part locally.