Hello to all you mechanical minds. My 560Sl 1986 Speedometer just plain stopped today. Working fine all day, looked down after turning on the lights and needle is at 0mph. The odometer and Tach work fine, all other gauges work fine.

ADDITIONAL;
All Items lights instruments in the vehicle work and deduct that no fuse is blown. Is this an electrical spedo and how can it be tested without removal?

Other suggestions appreciated

Thanks, Jack M.