The cap on the MC just keeps dirt out and fluid from sloshing out. They don’t seal the pressurized side of the system.
I checked mine, pedal moves 1-1/2″ and the (new) pads move 1/16th total for both sides. Brake rod is on the top hole on both pedal and lever.
Are you pads almost gone?
FAA certified jet engine and aircraft technician,
Nicholson Speedway class champion 2001,
Yamaha KT100 Service Center,
41 years karting experience