I’m pulling my hair out with this one. I have a 2017 sportsman xp highlifter. I replaced the front pads and the left front caliper, caliper was replaced because one of the outer tangs was broke off. Prior to this work both my hand brake and foot brake worked perfect. I gravity, power, and vacuum bled the system but I have no handbrake (goes almost to the handlebar before it does anything) but my foot brake works perfect. I replaced the hand master cylinder with no change and bleeding with all three methods. I tore off plastics to figure out my routing. My hand master drops to a distribution block that has four ports. Two ports go to my front calipers. The other port goes to my foot brake master cylinder/proportioning valve. I found a bleeder screw on my foot master cylinder, I bled that, got lots of air but still no change. After the foot master cylinder a line goes to another distribution block with two lines coming out going to each of my rear calipers. No fluid is leaking, all calipers are moving on their pins like they are supposed to. I cannot find info or understand how the proportioning valve works. Is it possible that it is only supposed to all a small amount of fluid pressure from the hand master travel to the rear calipers and that seal or spring has failed and when I pull the hand brake to much fluid is traveling to the rear causing this issue?