This just started a couple days ago. My speedometer will work from a stand still, get up to say 50 mph and drop to 0. It may stay there for 5 minutes while I'm riding and then jump back up and work the rest of the ride. Yesterday it jumped around the entire ride. Today it did it for about a half hour and then worked fine the rest of the day. Where should I start looking for a fix? Everything else is working fine. Even my gas guage works!!! Tach is fine!