everything works fine until it quits I believe that [3amp] fuse is for both the instrument lights and the tail lights - I'd suspect more likely you have a bad connection at the switch to the rheostat or the rheostat has gone bad
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
I believe that [3amp] fuse is for both the instrument lights and the tail lights - I'd suspect more likely you have a bad connection at the switch to the rheostat or the rheostat has gone bad