Was wondering if anyone has run into this problem. When the shower is turned on the shower head only puts out hot water. It is a set up with the Hot and cold knobs. Then it has the center piece twist to turn on shower. If I turn on the hot water knob the water coming out of the shower head will get a little cooler but then I lose water pressure. Any ideas on this? I was thinking of replacing it anyway but didnt know if that would fix it.