My single handle valve in my bath stopped working. If I have it set on cold all is well, but when I turn it to add hot water to the mix the handle is pushed forward and all water flow ceases.If I apply pressure to the handles the water flows. If I turn the valve to a cold only position, the valve operates normally. The first sign of trouble was the loud thunk as the valve slid out and the water flow ceased when I was shampooing my hair. ( figures) I have not been able to identify the maker as yet. The valve is now behind a tub surround as the ceramic tile wall started to deteriorate a few years ago. I will have to break out a closet wall to get access to the valve from the other side of the wall. (I did not build this house, nor did I install the tub, I know there is supposed to be an access panel.)

When as it turns out, this is a Koehler valve. There is no cartridge to change. The valve required rebuilding with a kit that I found at Home Depot. The failure point wasd a rubber boot that opens and closed the ports to the mixing chamber. Once replace and new gaskets and valve face installed all worked well.