Re: Master cylinder / booster seal?
Yes I agree with the above: I recently recoed my Master and there was no seal there.
I was going to put one there, until I considered the disadvantage of not seeing a leaking Master if and when it occurred, when, with a superfluous seal, the leak would possibly fill the Vacuum Chamber, until you'd be alerted by a falling Fluid Level.
"GOOD BETTER BEST: NEVER LET IT REST: UNTIL YOUR GOOD IS BETTER, AND YOUR BETTER, BEST"
( Furphy WW1 HORSE-DRAWN water-tank end-plates)