Remote LP gauge not working

A note- the sending unit can become uncoupled from the magnet on the inside of the tank- you can usually get it working again with a magnetic tip screwdriver to move the gauge.

There are two styles of LP gauge/sending units typically used on the fixed ASME tanks in RV's. One is the "two screws" style mentioned, and the other is a snap on piece. Both of them are magnetically coupled to the internal float assembly, and can be changed regardless of how much LP is in the tank. Check which style you have, and both can be found at most RV stores or online. eBay often has a good selection of them at reasonable prices.

If it one of those button ones with one wire going to it then yes. Just take the two little screws out