[Bob In Ct]

If the rubber lines going to the calipers are old they will swell. The fluid can get to the pistons because of the pressure the power brake unit supplies. The problem is the fluid cannot return because the swelling overpowers the return pressure. This happened to me on my street car. the hoses were the last thing I changed, and the cheapest.

It was always worse following hard use of the brakes. Two hours later they were fine,. Trust me!

Bob