Have a shower problem in one of my rental units with a Moan faucet.. No water comes out of the spout when I turn the knob either way for hot and cold. I purchased and replaced a new cartridge with the same results. I then removed the cartridge and turned on the water and got a full stream into the tub, so no water supply problem. I then turned the cartridge 180 degrees and same problem. Any ideas of what my problem could be? I don't relish the idea of tearing out the wall to replace the faucet.