Originally Posted by Wolfedog50
The booster is the big circle thing behind the master cylinder. Brake fluid leaking into the booster can be very bad because it can destroy the booster. You will have to spend twice as much to replace the booster and the master cylinder if enough flud leaks in and damages the booster.
Right; what he said. In my case it'* not leaking into the booster, but is leaking to the outside... anyhow, gotta get that fixed soon.
(I remember working on an old Cutlass where the booster had gone bad and would apply the brakes by itself, hard, as soon as you started the engine. That was seriously weird...)