I had a Warrior a very beat up old thing but it shot well. Being a concentric design there were two washers an internal one that went into the piston & sealed the barrel to piston plus the main outer one that sealed the piston to cylinder.
The main leather seal was held on by a thick washer that was slipped down over a turned down portion of the piston that extended forwards, this was split into approx 6 segments & spread out to hold the outer washer in place.
Of course dry firing would smack this into the end plug ferociously & two segments had actually snapped off in the past. Not sure how you would get a new main washer on there with out some serious engineering.