I have a tach installed on my 2002 883. It's OEM but was installed by the bike's prior owner. It just started acting up on me. The needle is jumping all over the place. I will be riding along and it appears to be giving an accurate reading, when out of nowhere it jumps in the redline and then starts bouncing all over the place. I suspect a loose wire but am not sure where to start troubleshooting. More than anything it just plain annoying and distracting.