Hello everyone, I'm new to this website. I'm a super for a senior community and I find myself doing a lot of plumbing work lately. I'm a carpenter by trade and get a little uncomfortable if I shut someone's water off and cant remedy the problem. It's like hit or miss when I do the shower valve. I tried to youtube it and see a lot of different techniques done. Basically either the knob is hard to turn or water doesn't shut off all the way. When I fix one I don't know what I did differently from the one I cant seem to fix. Can someone help me?