I would suggest first taking it apart and checking the bore for scratches and or rust spots. If the scratches or rust spots are not to bad you can hone the master cylinder with a wheel cylinder hone and rebuild it. I am not sure where Ellis gets his cylinders but there may be rebuild kits available. If kits are not available you can probably buy a new unit from Ellis. His first name is Bob and his number is 818/361-4011. Give him a call and he will most likely be able to help.