Actually, Grainger Supply has been my best friend when it comes to o-rings. I just walk in, and they size them with their caliper. They typically have most sizes I need. I love the variety of items some of the online espresso vendors have, but I have a hard time justifying buying a $.60 cent o-ring for $6.00 dollars.
As far as 'other parts' are concerned it really depends on the project. I restore the machines with all original parts, so it really just depends on how rare one is versus another. For my Conti Prestina I had to source a lot of parts from Allann Bros. in Eugene, OR. That was an extremely expensive endeavor. I had to replace the pressure gauge, all 7 lever bearings, the site glass / site glass gaskets, piston o-rings, the odd sized c-clamps. . . those 'small' things added up to about $350 alone. The crazy thing is Allan Bros. is one of the original Conti distributors in the U.S. When Conti stopped making the Prestina the owner of Allan Bros. had enough insight to save 10 Prestina's to sell for parts in the future. I got 2 of the pieces off of their last machine. . . and Allan Bros. was the last distributor with original parts.
Anyway, sorry for the tangent. I find that most industrial plumbing companies have the PEET Virgin Teflon to make gaskets, and they are usually willing to make custom ones for you. . . again very expensive. I replace all of the screw, nuts, and bolts withe the highest grade available in each size. For that you have to go to a screw specialist. Powder coating has to be the most fun part of the whole restoration for me. I have kept my machines true to their original color thus far, but they can powder coat in every color imaginable. There is nothing like bringing in an old rusted internal frame, and when you pick it up it literally looks brand new. The orange on that San Marco will look amazing!
Hopefully I answered most of your questions somewhere in all of that
. Sorry again for the tangents. Restoring old levers brings me a lot of joy!
