Tach/Speedo Problem
 

I have a NA 1988 944. I had it sitting for about 7 months while I was away. Only taken around the block once a week. About a month ago the rear driverside tire went flat. I jacked the car and took it to get fixed, it was a simple fix. Then the next week when it was taken for its short ride. The tach would only go between 500 and 1000. Then on second ride after that the speedometer was staying low also. Although the car ran fine. I must have done something to the tach/speedo sensor which I think is on the rear driverside tire. Any suggestions on what to look at?

Speedo transmitter is on the top of the axle stub on the trans drivers side. Tach gets it's signal from the DME. I don't think the flat has any connection.

But! The grounds and connectors for the instruments do. Have to pull the instrument cluster to get to them.