Need Expert opinion

[ubtripn]

I just installed a new Master cylinder. I have 4 wheel drum power assist braking. I did have some squealing initially like a balloon being emptied by stretching the opening when braking but way louder. I removed the MC and lubricated the dish in the power booster that the MC mounts to and it went away. It was braking GREAT but I still had a little air and travel. I could not get one bleeder screw in the rear out so I had it bled by a machine at a shop. I think but am not sure that the front tires are braking as before but I am now using more force than I do in my 66 that is not power assisted. Is it possible the booster went bad or the MC? Thanks in advance for your info and help.