For those of you replacing masters, It's a good time to inspect / replace the wheel cylinders and calipers as well. Had one just this week that I assumed were fine due to us replacing them ~ 10 years back. For some reason after all was done and bled I decided to pull a rea drum and the W/C was just damp with fluid. Peeling back the dust seal revealed rust . So, I got to bleed the system again after replacing the W/C and calipers