When I apply the brakes in my duece they stay locked up. I have to un screw a brake line to releive the pressure so it will roll again. I put a new master, bled the brakes and dismanteled the air ram and appears to work ok. One thing that my master does not have is a vent tube comming from the fill cap that I have been reading about. Not sure what the cause is. Any suggestions? It is a 1965 kaiser model.