Pete what does the brake fluid in this car look like?? If it was sitting a good bleeding may be enough to get the moisture out and free up the proportion valve. Also try a replacement check valve on the front of the booster.
Ron
not real sure on the fluid car was sitting for a long time with the owner only driving very little the last few years the car is officially sold now the new owner has said that he is more than capable of doing whatever repairs are needed on the car, so the original owner has agreed to let the car go to the new owner with what ever items need attention. Wishing the new owner lots of luck with the car, it's a rare piece even though it's a 73 RR it does need tlc and after getting to know the new owner a little bit more it really sounds like the car is going to be in some really good hands now. Thanks to all who have replied.
