If that switch is completely exposed underneath the rig, it might be collecting a lot of road dust & dirt of which could cause it from working consistently. Once back home, remove and inspect. If it isn't corroded/rusted, I would just clean it good with an old tooth brush and dish water, not lube it for concern it will collect dirt much more quickly. If rusty, soak it with a CLR type of product, rinse, dry, (maybe clean with old tooth brush too) and douse with WD-40 to protect it from rusting again. But then plan on cleaning it much more often.
Glad to read keelhauler's solution got GoPhoenix problem resolved. This is a great forum. A "Helpful" from me to kh.