98 216 Coupe Speedo Problems

[davamer23]

Hi, can anyone tell me /point the way to a cause/fix for the erratic speedo-odometer on my 216? It keeps fluctuating wildly and mostly sits at zero regardless of speed, also the odometer will only tick over when the speedo is registering. It's now an mot fail so wanna sort it ASAP. Cheers in advance for your help.