My gas furnace will not turn on. I verified 120V where the armoured cable enters the furance, so I was going to continue testing for voltage before and after the transformer (with the door safety switch pressed in and 24V call-for-heat manually triggered, flame safety module is good), but I noticed a broken bit of (aluminum) wiring at the green ground screw. The black and white wires are solid copper. I assume the aluminum wire inside the armoured cable is ground, and was wrapped a couple times around the outside of the metal sheath, and then finally connected to the green ground screw.
Is using a short strand of solid copper ground wire, with the copper wire screwed into the grounding screw, and pigtailed to the aluminum wire with an AlumiConn the best practice?
Quck note - I'm comfortable and confident with the gas-related safety components on a gas furnace, but aluminum wiring requires special knowledge and is a source of fires, so I'm super cautious.