73 Valiant Intermittent Headlight Issue

Have a good look at the dimmer switch/plug on the floor.
They take a lotta abuse and debris/water .
Thank you for your response here...
Dimmer seems okay when the lights are working Hi -Lo Beams interchange *(Oh Yea - and it doesn't affect them coming back on unfortunately *(see reply to Car Nut here) but could still be the cause of a short maybe? What's a good test for the Dimmer Switch?
In fact - I now wonder if a short *(in the dimmer or wiring to/from & or water) could have caused the switch itself to go bad initially?
Yes wires on the floorboard can definitely cause issues but I Do so love the Dimmer Switch~On the floor where it belongs.