My 940T speedo mostly registers up to 45 MPH but usuallt does not go higher. Occasionally it will indicate the actual speed, in cool weather and ?? cnditions.

My question is it worth having the unit serviced and repaired or should I replace with a used or new speedometer? The odometer works fine and always has. The speedo gradually tops-out at a lower speed during a long drive.

Could this be related to the ground screw or loose connection? It seems like mechanical drag to me. The car has 248K miles in SE climates. The needle does not jitter or spike when traveling below 45.