I think we solved the problem.
The car has a remote pressure guage that runs down the length of the front frame, pretty close to the header. When we rebuilt the system, I did not realize I had to bleed the guage. Thus there was a big air pocket. As the car heated the air expanded and it somehow locked the master. We are going to give it a try tonight and see it it solves the problem.
Thanks for all the help.
Al