I had already removed the knob, the screw, I had to drill it out, the chrome cover, to gain access to the mixing valve that sends water to the shower head. I cannot get it out for the life of me. I had removed the clip that holds it in place, and it still wont come out. Has anyone else had issues removing this? I went to school for plumbing, and this is the first time I had this happen that it wouldn't come out. HELP!!!