There is this excerpt in the Tank Off Maintenance Checklist:
>Find the straightest, gentlest routing for the speedometer cable. Make sure it is not crimped, kinked, or bent. If you have an early V11 with the white face Veglia, service those bevel drives, especially the one at the gear box (the upper is attached to the back of the speedometer itself). Make sure the brass insert is pressed well into the body of the drive and consider permanently sealing the metal disc before it goes missing along with the internal worm gear!