Originally Posted by kazoo

Inside supply piping I've found beads of solder, faucet washer screws, faucet washer fragments, etc. Remove the shower head and see if you can get a good flow from the open pipe. If not, shut off the supply lines and disassemble the hot/cold/diverter valves and look for an obstruction, as well as a loose valve seat (assuming older style valve assembly-not applicable to newer fixtures).