1950s 1959 Cadillac headlight switch

[Eric DeVirgilis CLC# 8621]

I'm not sure cleaning the rheostat will help if it's heavily worn. Years ago I ran into a problem of intermittent dash lamps and my mechanic simply bypassed the dimmer so they would simply illuminate to full brightness whenever the headlights were turned on. It never bothered me since I always have the rheostat set to maximum anyway as instrument panel lighting isn't very bright to begin with.

[Cadillac Jack 82]

Well as soon as I posted that and stopped for a beverage, they stopped working again.  Easy fix but frustrating.

[quadfins]

There may be a break in the rheostat coil, that intermittently reconnects.

[Cadillac Jack 82]

There may be a break in the rheostat coil, that intermittently reconnects.

I believe that 100%.  I noticed some odd things happening while trying to twist it back and forth.  Other lights would flicker on (such as the high beam indicator or GEN light). 

[Big Fins]

This may get interesting. You may also have a break on the printed circuit board. Just about every bulb on the dash is run through that.