How do I find out the size of the resistor I need for my quartz heater?

Question

Markings on the old resistor "IN 540 DC" with only one silver band.

Answer 1

I don't think it's a resistor. It may be a diode, A # 1N540. Let me check my references for specs.
Yes, definitely a diode, the band denotes the direction of current flow.
Any electronics part store should have a substitute for it. But the more common 1N4005 is easier to find, cheaper and actually has a slightly higher rating.