When I press the shower diverter on my bathtub spout to turn on the shower there is a noticeable "thud" and the water doesn't come out of the shower (or the tub spout either). Sometime there is a noise like a water hammer. I have checked the shower head and found no clog. I have replaced the tub spout also. I think there may be a problem in the "disc" (?) faucet (Single handle to select hot and cold water with center twist knob for velocity) , but what do I know. Any ideas?

Re-Shower Head Won't Flow..still

Just Started