My dad was a machinist. In the 60's he worked for a company that built military radar units. This was back when analog electronics were the rule. These were machines with big knobs to adjust frequencies and such. The cables inside the units had to move very smoothly so one of his tasks was to machine the Teflon guides and rollers inside the control units. he was amused that there was nothing that thy could use to "glue" the Teflon down, so guides had to be screwed to the chassis. I still have a 6" length of hollow rod (was used to make rollers) and a solid piece about 6" x 1" x .25" which he brought home.
7x2 would be easiest made using a 1/4 " center punch on a 1/16" sheet. this part must be a steam or water valve end seal or a blind cap seal? if yours is missing you can make one but if it has a wear ring on the surface just flip it over.
Got em from Bill at EspressoWrench, Magister uses the same I think is what he relayed to me. Stefano and CafeParts sameday feedback, notfirstinline no response(not surprised)
I've been looking for an affordable source of virgin Teflon in small quantities. It's not the easiest thing, with $20 line minimums, $30 order minimums, or silly-high shipping charges. Enco (machine tool supply house) does have it available in reasonable sizes. http://www.use-enco.com/ and search on "virgin"