Yep ohms is what you want to measure resistance. Looks like an upside down U. The resistance to current flow with voltage being the pump or pushing force. Simplified a high resistance joint etc. in the circuit will cause a low voltage where you need it. I doubt if the thermistor is faulty. The whole power train needs to be looked at from the 12 volts ac out of the transformer which plugs into the power driver board at j101 and then through the rectification circuit to give you the 5 volts DC and then on to the CPU board. Your problem could be one thing or several things any where along the train contributing to the low voltage. As others have said beaky is your man but you could do some minor testing yourself for interest. Be carefully though as you can cause more trouble for yourself and more expense if you short something on the boards when powered.
