So check the connections on the back of the tach. Loose = jumpy operation. You will also find a calibration dial on the back. Note the setting -- then with a small screwdriver, rotate the dial back and forth several times to burnish the internal contacts a bit. Set the dial back where it was and so if that helped. You might find repair of the tach is more costly than replacing it. You can get a new tach right here on iBoats or if you are dead set on an exact match, you can try "great Lakes Skipper".
Silvertip, I know all those tricks. It's cluster of gauges, they can't removed independently. The mechanism is behind (or in front of) the gauge panel, depending how you look at it.
Have ever heard of Uni Force?
there are places on the web that advertise rebuild services for dash boards. most of them you remove then you can get to the screws to get inside the unit. silvertips is correct that jumpy equals loose so check the plug connection for the dash first before going to far. contact cleaner might be a good idea to clean the connecter. also remeber theres 2 ends to every wire
