My machine is about 10 years old, with a single red switch over a green light. Recently the switch burned out, I ordered a new one and they sent the wrong part. I installed it and threw the switch to the sound of a pop. Not good. I called the parts supplier and found the switch was for the older dual element version. I got the right switch but it quickly went to feeling "soft" in the on position and the red light won't stay unless you are pressing it. A repairman told me it could be a short or the element may be wearing out. I have bought two switches, the element had never been replaced but I rebuilt the machine otherwise (new gaskets, piston and ring). How can I use a multimeter to troubleshoot this? Instead of just replacing parts.

If the ohm reading roughly equals the voltage squared divided by the power, you're good. Anything else, and you're not (or more specifically, the element).

2 prong la pav heating element should give you about 14 ohms
make sure your wiring is correct

Michaelburke wrote: I got the right switch but it quickly went to feeling "soft" in the on position and the red light won't stay unless you are pressing it.

I've seen this before, definitely wiring. It's a good idea to take pictures of your wiring set-up, switch and heating element, prior to disassembly.

Pavoni Express Website diagram

Michaelburke wrote:Recently the switch burned out...

You don't see this too often, especially on a L.P. only 10 years old. Do a careful check of all of your wires and connections. An electrical problem usually blows the fuse, trips the little red breaker or totally does in the heating element.

Did water penetrate the inside/underneath?

Michaelburke wrote:How can I use a multimeter to troubleshoot this?

A continuity tester is usually all you need for troubleshooting espresso machine electrical problems.

Michaelburke wrote: A repairman told me it could be a short or the element may be wearing out.

It would be unusual for a 10 year old Europiccola heating element to be wearing out. They are mostly either alive or dead.