Has anyone rebuilt their Master vac?

Looks like I have a leaking master vac. Have lost all power boost to the brakes (brakes themselves are OK.) I hear a noticable hiss upon depressing brake pedal (and for some reason, engine speed increases about 500RPM). When I disconnected the vaccuum hose from manifold to the master vac, the sound disappeared.

There's not much info in the Chilton manual I have about the master vac.

Is is worthwhile rebuilding it? Are bebuilt ones available. How difficult is it to remove? I can see a real problem working in the tight space under the steering wheel. I'm wondering if it's best to hire this out.

Any comments appreciated.

Jon

thebigboy@earthlink.net