PowerMaster Problem / New to Grand Nationals

[thegerm]

Hey guys this is my first post. I just purchased an 85 Grand National. I towed it home knowing the car has sat for a long time and the brakes didn't work. The car runs.
I got the car home and in the barn. I noticed that the switch was unplugged on top of the power master so I plugged it back in. The brake pedal is buried to the floor weather the car is running or is not. After I plugged the switch in I started the car and hit the brake pedal I noticed no difference in the pedal height . I then turned the car off and tried to roll it in neutral to put it up in the air on a hoist and all 4 wheels were locked. I ended up jacking the car up and found that the brakes were all applied. I cracked the bleeders loose and the wheels freed up after doing that. I assume the master cylinder is bad on the power master setup. I just want to see what you guys think.
Thanks,
Jeremy

 

[longball]

Read this:

http://www.turbobuick.com/forums/threads/powermaster-brakes-diagnostic-information.362564/

and this:

http://www.turbobuick.com/forums/threads/the-powermaster-bleeding-procedure.218912/

then post up some questions