1985 chevy 350 with hydroboost

Have new master cylynder with old hydroboost.. even before I got the new MC, every once in a while the front brakes slowly siezed up until full stop. I think it is the pin inside the hydroboost pushing the master cylynder. It dont look lke there is an adjustment but I was thinking about putting a GASKET in between the MC & HB to give the pin a bit of clearance, I am NOT a mechanic. This motor is in my 1985 Lazy Daze 22 ft class C motorhome that I shipped over to Australia from California. The hydroboost works according to the 1/4 depress test etc. Just seems like the pin sometimes goes in to the MC just enough to mess up the front brakes,..HELP
Hank in Melbourne Australia