When you put it together, put the rubber ring in the M/C opening first. Install the M/C on the firewall. Don't forget to bench bleed the M/C first. lightly spray the end of the pushrod with wd-40 or similar. Push it into the M/C. You might have to attach the pushrod to the brake pedal and use your foot to push it in. Next time to remove the pushrod, back off the nuts that hold on the M/C so they're flush with the end of the studs, and put a shim of some kind between the firewall and the M/C to shug it up. Go under the dash and with two hands yank back on the brake pedal really hard. Usually this will yank the pushrod and retainer out of the M/C. Why didn't you just use the new, aluminum M/C?
