T3 '82 model vacuum leak in brake booster

[Andy.]

only an issue when you push the brake pedal - no leak until then. web points to faulty seal / corrosion b/w booster and master cylinder or booster diaphragm holed. 
it does not seem that hard to remove the booster to check - but is there a way around having to disconnect the hyd lines from the master cylinder, i really dont want to bleed the system as its not required ATM and a real pain.
any tips / pointers for this issue would be appreciated.
i see new boosters are available if that is required, has anyone had luck with re sealing the junction b/w the booster and master cylinder?
thanks, Bruce

Just curious when you say there is a vacuum leak? Normally that would wither affect the engine running (runs lean if the booster or vacuum lines have a big leak), or you need to apply a higher than normal pedal pressure (booster not doing it's job).
When you say it only leaks when you brake, that would be normal as there is a balance across the diaphragm until you brake. What are the symptoms though?

The boosters are tricky to get our (I assume it's under the dash like late T3's??). And unfortunately, yes, the master cylinder needs to come out also. They are not that bad to bleed, pulling the booster out is a bigger job!

Yes if it's an old original booster they can certainly get corrosion that affects them operating (not necessarily leak though). The diaphragm themselves are often good. I've re-built a few Bay window boosters and not needed to replace the diaphragm. The master cylinder bolts to the booster, so there's normally just a gasket there. (I've re-built Bay window and late T3 brakes, not an '82 but expect they would be similar).

As for tips, I'd certainly check all the vacuum lines from the engine to the booster, especially connections and the non-return valve before pulling the booster out. These are more likely to fail.