hi George,
Sounds like your master cylinder is leaking fluid at the plunger and you'll need to address it else the fluid will find it's way into your brake booster and ruin the diaphragm. The master cylinder will need to be replaced (or rebuilt if you prefer that route). There's a seal between the master cylinder and booster and as I recall, the new master cylinder includes a new seal. Install your old reservoir onto the new master cylinder using a Reservoir Mounting Kit. The kit is available from a number of vendors - I got mine from Bud's. vr,,charles