Brake master weeping

I have often found that seepage at the M/C is being caused by an excessive return of fluid to the reservoir.
Less often occuring when the rear shoes have excessive travel (pedal was mentioned) and the springs pull the shoes a LONG way back.
Most common is air in the affected system compressing like a spring, and when you release the pedal, the fluid forcefully returns to the reservoir, blasting against the rubber seal.
Easy enuff to check,.
Set the emergency brake. This moves the rear shoes into contact with drum, and when you pump the brakes, the w/ cyl will fill and push the pushrods out to the shoe.
The rear wheel cyl cannot create any reverse pressure with the emerg on.
Have someone pump the brake pedal a couple times, and hold it down.
Remove the cap, and have the pedal released, and watch the reservoir .
There should be very little disturbance in the large reservoir (disc).
There should be more disturbance in the small, - if you have a strong return or geyser/fountain into the small (rear) reservoir there is air in that system.
(Remember the rear cyls can't push back).
Getting rid of the air/spring will often resolve the weeping .
The seal is to stop sloshing, not a forceful blast of fluid.

BRAKE fluid is excellent paint remover, so protect and thoroughly rinse with water, any fluid splashed on the paint ! ! !