Brakes....

Dougo,

The only other vacuum related part in the system is the metal tube that runs under the car with the water tubes. After 30+ years, it is conceivable that it could have a pin hole somewhere in it. This is just a guess.

You can test it if you want to by disconnecting the hoses at both ends, capping one end, and filling it from the other with compressed air. You can use one of those rubber tipped air nozzles used to blow dust and debris from a work area. It should seal right up to the hole. Hold it tightly against the tube and fill it with air. If you hear any whistling, there's the guilty party.

Michael

Thank you Michael for your suggestion. When I replaced the hose from the booster/check valve to the line under the front of the car, the original line has been replaced with copper tubing. It looked like the tubing was in great shape. I will go ahead and check the line just to make sure, It's not very hard to do. I'll let you know what I find.
Thanks again.