Wow, still at it.
Actually I am glad this thread came back up. My car is all in pieces again- I pulled the engine out for work and then removed the windshield and dash and everything behind it for restoration. It would be an ideal time to try the "paperclip reset trick" since my block is now very easily accessible. Guess I first need to put the brake pedal assembly back in the car in order to test it though
I did pull the top off my original block and looked down into it though. Not much to see.
I think that the danger of pulling and plugging lines at the combo valve is that if you get air in the system it could give you false readings. My suggestion- hook it all back up, bleed the system and then repeat your test- plug the front of the master and see if you get a hard pedal. But then if you do get a good pedal, reconnect the front and plug the back and see what happens.
Also check for continuity at the switch while you do this. If it does not trip the switch then something is wrong there, because you will only be putting pressure on one side of the system.
Walt