Dwight,
If I recall correctly, you indicated in another thread that you had drilled and tapped a separate line from the hydrovac into the master cylinder resevoir. I think I see that line going into the side of your master cylinder in pic #2. Is this the line that you say "feeds the hydrovac"? I don't understand the function of that line. There should only be one line from the master cylinder to the hydrovac and then one line from the hydrovac to the wheel cylinders. Perhaps you can clarify what your connections are.
Your hydrovac vacuum chamber may full of brake fluid, which might explain the loss of "air release" sound. There are internal valves that can leak, filling up the vacuum chamber, causing loss of fluid from the master cylinder, without apparent external leaks. If that is the case a rebuild is in order.
If your brakes have been bad for several years, you may have multiple problems. If wheel cylinders are not "exercised" they will seize, so you may have one or several cylinders that are not functioning, as Don Stocker has indicated above, in addition to possible hyrovac problems. Good luck and let us know what you find,
Kent
