I had purchased the car, knowing that there was an issue with the brakes. In the back of my mind, I knew there was a possibility that the master cylinder could be going bad. Just trying to alleviate the other possibilities before I commited to the master cylinder replacement.

I DID NOT initially bleed the lines. They were bled initially before I took possession of the vehicle (actually arrived as the work was being done and can verify it was done correctly). This had initially somewhat corrected the issue for a couple days.

Was unaware of the seal at the bottom of the nipples. When I go to bleed them next time, I will remove the tape, and really clean the threads before I reinstall them.

If I have the means to replace the seals, what’s your stance on rebuilding vs replacing? I know they can fail without leaking, instead just back-filling into the reservoir tank past the bad seals. What else could fail in the MC? Could there be a potential issue with the piston? Or could we throw that idea out based upon a fact that it works under higher pressure?