I replaced all the gaskets a few months ago and it has been working flawlessly since. Originally bought with broken sight glass, also replaced. Two days ago the pstat switches off, light goes out, but the boiler continues to heat. The wiring is in good repair, but the boiler terminals are getting 60-80 volts AC even with the switch off. It shouldn't be complex, but I am not an electrician. Switch tests good. Ideas?

Not sure but the P stat might have failed.

Have you checked continuity throughout and from point to point using a multimeter with the machine unplugged? If you're not sure about how to do this perhaps you could take it to an appliance repair shop and have them check for a short. If the switch is "good" there should be no current to the heating element terminals when it's off. If the pilot light is working consistently the fact it's not lit tells you there's no current going through the heating element. Maybe you could clarify what you mean that the machine continues to heat and that you're measuring current at the terminals when it's off. How are you measuring?

Problem solved: The previous owner had replaced the plug. He switched the hot and the neutral. I am not an AC master and it took me a while to deduce what could be going wrong. So, switch replaced with very much more narrow pressure range (thank you very much) and working as it should with a few minutes of effort. Thanks for your help everyone.

That makes sense. I was wondering how you were seeing partial voltage at the boiler-especially when the circuit was supposed to be opened.