I am in desperate need of finding out how to remove the valve stem in my faucet. This is the bathtub faucet, single handle, and it will no longer shut the water off at all when you push the knob back in. I have everything taken off, but I am unable to remove the valve stem. There is no exposed hex nut and I have no way of knowing how to get to it as there is some type of brass clamp type of thing on the end of it. It has two grooves (notches) and as you can see from the picture, a little tab sticking up through the top notch. Any help would be greatly appreciated. Thank you.