That p-stat looks exactly like the one from my Microcasa. Congratulations, nice machine.
If your pstat is working, don't take it apart.
Mine wasn't working, so I attempted to rebuild mine with help from OE. I'd not recommend trying to repair it (if it's broken) since the lack of re-enforcing fibers in the replacement material allows it to 'drift' after a couple of months use. Probably best just to put a new pstat in place if you need one. There is a thread (somewhere or other on HB) that shows the rebuild, but once again, I'd not recommend it.