Hey everyone, new member here! I have a 2005 arctic cat 500 that I can't seem to figure out a brake problem. A while back my FIL drove the atv with the hand brake locked for a while until he figured out why he wasn't moving very fast. Since then my brakes have had an issue like there is air in the lines. I have bled the lines repeatedly and replaced one caliper. Bled the brakes again last night and still have the same issue. Hand brake will get firm and brake fine for a little while and then next time I'm on it it will be soft and no brakes until I pump up pressure again. Could the master cylinder be damaged somehow from what my FIL did? When the system has pressure all calipers are holding like they should and seem to release like they should.