If you remove the headlight switch and place a bit of 600 grit wet/dry paper between the wiper and the coil and rotate back/forth you'll clean the coil...if the sandpaper follows with the wiper. Then if you reverse the paper and wiggle it a bit, you'll clean the wiper. Things will work much better.

Now if you have a replacement (think Chinese) switch, you have a coil with a different resistance value. The OEM unit had about 3.2 ohms of resistance, but it was actually created by engineers with degrees and a proper plan and not people just copying what they see. The Chinese switches have anything from 10 to 13 ohms resistance and it all has to do with what value of resistance wire they had to use the day they made the switch. I posted about this before when I explained how to resurrect your headlight switch and again just last week when I explained Kanthal wire values and the effect they had on light switches.

This isn't to say the Chinese switches won't work. They will, but when you turn the dimmer from fully bright to dim, you'll only have to turn the knob about 1/3 of a turn...because you run into an ohm rating too high to make your lights burn. Please remember resistance means just what it sounds like...the more you have, the fewer electrons make it to their target. That's also why these coils are set into ceramic pieces...so they won't get too hot. So instead of having a switch that gives you a nice full range of dimming, you get one which gives you a short range of dimming.

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end