I recently acquired a Rancilio Silvia modded with a PID (using these instructions, according to its former owner) and a beefier water pump. The water pump works fine, and I can get water to come out of the brew head, but the boiler won't heat up at all.

I tried pressing the reset button on the overheat-protection thermostat, but the button feels loose and wobbly as though it's not properly connected inside. I tried bypassing the overheat-protection thermostat altogether, and the boiler still didn't heat. The heating element contacts seem to be shorted, with zero ohms of resistance between them. I suspect the heating element is blown, but is there a good way to confirm that it is really and truly dead before I send off for an expensive replacement? If it is indeed dead, do I really have to replace the entire boiler or is there a way to just replace the heating element itself?

Thanks for your help. This is my first foray into the world of espresso machine modding (and my first major electronics project since college, to be honest), and it promises to be very instructive.

Unplug machine, disconnect at least one of the heating element connections (to avoid other components affecting the reading) and then take an ohm reading. It should be about 10 ohms, if it is 0 then it is open and needs replacement. Whether it is worth while or as you mentioned needing total boiler replacement, I can't say. The overtemp item is a bimetal that feels loose when closed and "tight" when tripped.
Duke

Thanks for the tips. The heating element still reads zero ohms even when entirely disconnected, unfortunately, so I guess I'd better start looking around for a new boiler assembly. Time to start prowling Craigslist for more broken Silvias.