That is a resistor. In college I worked at Dale electronics in Nebraska where we made those all the way from crinkled flat wire on a 3 ft ceramic tube for French subway cars to thinner than hair size wire on a fiber rope soaked in a varnish, clipped and terminated for various ohms for Chrysler corp. For what you have we baked on a high heat paint for insulation and if it was a variable resister like you have would remove a slot of the paint to be able to make contact for a sliding contact along that slot resulting in varying voltage to the motor therefore varying the speed. Having the coating flaking off shouldn’t affect the workings but just potential contact with something it shouldn’t touch. Sparks/smoke not Good. Several coats of bbq grill paint with everything taped properly including the strip where the slider hits should do you. If you want more protection, the refractory cement may work as long as you’re not in too humid of a climate for it to absorb moisture. I would probably paint it first. Make sure that you keep that contact strip nice and clear of anything.
Larry
Old man᠁Old truck᠁neither one goes very fast. All you need in life is TIME, PATIENCE and MONEY.
If you are missing one component, you'll need an abundance of the others two.
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