Hi Dave,

I replaced a bad brake MC in my 740 with a "rebuilt" unit which luckily
had a lifetime warranty. Their idea of rebuilt was maybe to ignore the bore
and replace the seal. That's when I learned to avoid rebuilt MCs.
I think they replaced it maybe six times.
Probably I wrecked the new seal by bleeding with the peddle and finally made a power brake bleeder to avoid sending the MC piston into the nasty deep seal damaging territory when bleeding.

I was always amazed how stubborn some of those bubbles in the clear brake line tubing for bench bleeding the MC refused to budge even with a lot of tapping.
Since then I've wondered if the perfect tool for shaking those stubborn bubbles out of the MC, calipers and brake lines might be to use an electric palm sander without the sandpaper and just press the rubber pad to the MC when bleeding,
and the calipers when doing them. Maybe others have tried this?

Happy Thanksgiving, Bill