fuel gauge isn't working. who would have guessed? it's stuck on full, but the low fuel light works fine. I took the cluster apart and tightened the nut in the back, to no avail. I tested the sending unit with a dmm and it tested perfectly fine (~60 ohms at empty, 0 at full). so I need help figuring out where the wiring disappears to so that I can check continuity. is there also a chance that the gauge itself is bad?