The booster is attached to the master cylinder. I <font color=red>replaced the booster</font> because it sounded like a blew a seal one day and then I had no brakes. I <font color=blue>left the original master cylinder on orginally but my brakes were quickly locking up</font> . <font color=red>Then I swapped out the master</font> cylinders
If it started after the booster replacement, that's where I'd look. Is the rod on the front of the booster adjustable and did the instruction sheet that came with it say anything about checking the length against the old one?
You also said
I release the master cyclinder and they work again
What method of release are you referring to???
