I had the same problem with the speedometer on my '97 Nitro. Turns out that the tubing that runs from the lower unit up to the speedometer got pinched in the transom hinge. It looks like someone tried to repair it before and didn't route it properly. Then again...if the had to repair it to begin with, it probably did it before.

If Monroe doesn't fix that stuck fuel guage...go try Brookville on any summer weekend with a North/South wind....