[T3] Master Brake Cylinder

[J. Jonik]

Re/  '71 Std.
    A couple of weeks ago, a good brake bleed job got questionable brakes back to Almost Normal.
   Now, having worked half-decently (not perfectly) a few days ago, and having not been driven for those few days, there's barely any brake pedal resistance.  Pedal goes way down.   And pumping the pedal isn't bringing back any resistance.


The last time I was checking things, there was wetness in the slightly-damaged rubber boot between pedal and master cylinder.   No drip puddles under the car at wheels or anywhere.
   Is this evidence that the Master Cylinder is faulty?   How to test to be sure? Should that rubber boot be dry inside?  And should it definitely be replaced in any case? (It's just to keep dirt out, right?)


Then, what's advice on picking a good spare master cylinder from my collection?  If they are still wet from brake fluid, not dry, is that a good sign?  I kept some wrapped in plastic bags.