You'll need to ensure there is a good frame to smoke unit frame connection, ensure the wire or unit tab isnt shorting, and finally checking for continuity over the resistor (or element, same resistance) (fame to tab should have continuity)
No meter? Jump proper rail power to unit frame and wire to test just the heater.
In nuetral, and or jumped, power high 14-18v+ if you have it, wait a minute or two just sitting there to warm up well. It would smoke if it is going to by then.
Change the element if needed (rebuilds of pellet heaters on ebay or maybe one of our venders? Or just switch to a resistor type and move to fluids..... always get new packing for this job. Always replace the gasket if that has no spongey rebound. Ni-chrome element wire doesn't stick to solder, you wrap and trap it in the solder.
Both heater types are simple, two wire affairs. One wire to frame, the other a lead to a roller connection.
That hand wrapped ceremic(cooled) pellet element could take up to 25v in stride, while a reistor somewhat less and should be kept wet, to cool it.
Optional home spun- cheaper- heater can be made with a normal metal wapped ceramic reststor of the right OHM and griding off ceramic shell until the innner metal wire is exposed. idea is from GRJ
