When the tripometer on my 1981 240D stops working from time to time, the odometer stops too After a few pushes on the tripometer reset knob, they both start working again. What is causing this?

I’ve never taken one apart but I remember reading a long time ago that some of these have plastic parts that get brittle over time. The advice was not to use the trip-meter any more than necessary and not to use it while the car is moving to prevent jamming of the components. I don’t know if that was true but it seemed logical. Consequently I don’t use mine.

JohnM 1983 240D 4sp 152K