master cylinder

Just purchased a 415C s/n 4375 and it had virtually no braking because the pedal was almost to the floor and did not return.
I made only 2 landings with it and was not going to do any more without investigating. Removed the cylinder (what a heckuva job)
and found that the piston was hanging up severely mid-travel. Cleaned the bore out with 600 grit paper. The piston now works like it should.
The coating on the bore was very dark looking. Apparently moisture in the 5606 can cause this problem.
You have probably fixed it by now.

I do not have this problem, but I have my cylinder out to fix a leak on it. o-rings ordered from Skyport. I will let you know how it goes back together.

It's a pain to get out!

The brake master cylinder does not return sufficiently for the brake fluid from the reservoir to refill the cylinder.
Seems that the friction of the new o-ring seal is greater than the return spring force. I have rudder pedals and the hand brake cable remains slack.
Has anyone had to resolve this problem??? Thanks, Joe Loomis 415-C, N-93712