Thank you for the results. They show that the potentiometers are not open-circuit, the rotary wipers are able to make contact with the circular track. In the case of the wirespeed control, that was important because the pot is right at the start of the speed control circuit.
I think the next steps are to test all four positions of the Mode switch, whilst operating the torch trigger and, if applicable, varying the timer controls, to compare what happens with what should be happening from the descriptions in post #34, and then to check the two power supply voltages on the board, as in post #36.
I think the next steps are to test all four positions of the Mode switch, whilst operating the torch trigger and, if applicable, varying the timer controls, to compare what happens with what should be happening from the descriptions in post #34, and then to check the two power supply voltages on the board, as in post #36.