71 510 headlight issue

[squatches]

since ive owned my 71 510 the low beams have never worked, ive cleaned took apart the switch, relay and fuse box and cleaned all of them and sanded down all of my grounds and still nothing. And when the switch is on high beam the outter 2 lights are really bright and the inner 2 are really dim, almost not even lit up. if i pull one of the fuses for the lights these get brighter, but has no effect on the low beam setting. any ideas or help will be greatly appreciated.