If you have a 2001 Europa G500, then you are seeing a step wise movement of the speedo needle. It seems like it is just a early "digital" version, not at all smooth analog like the 1999 and very early 2000 G500s.
I think it is supposed to work this way. Maybe it was integral to the design as a cool digital feature. What did the repair place say about it?
I find it mildly annoying, but the readings are accurate.