Re: fuel guage????
I picked one up at Damark Marine in Gibraltar for my tank. I think it was 24.00. Universal, cut to fit dimensions of tank. In the case of yours, I suggest removing it from the tank and working the float arm all the way up. If your gauge reads full that would eliminate the wiring and gauge. Then you just have to find out if the float doesn't go to the top as installed in the tank. May be saturated causing it to suspend below top. Could have an obstruction preventing it from reaching the top.
Replacement in mine reads WAY past full now when full. I am only on my first tank of fuel after the change so I am am still trying to figure out what the readings REALLY mean.