Speedo no working - sometimes!

[DAMO 40/172]

My speedo seems only to work went it wants to. Can work for 20mins then stop for a couple of hours. Seems to stop more often when at motorway speeds. All other dials ok just the speedo.

Any ideas why and how to cure it?

 

[DAMO 40/172]

Bump

 

[eddy911]

me2, it usually stopped for > 110 KM/H