Thanks for that. Much appreciated.
I let it run for probably 10 minutes or more and there was no discernible heat at all.
I'll check the voltages, but given the resistance readings I'm thinking the fault lies up in the panel.
I'll give it another run and check voltages, but I think I'll end up having to pull the door apart and have a look at the controller/relays.
Are these boards/assemblies available if this is the fault?