I have an old cast iron clawfoot tub with a 1 piece faucet/shower diverter. We have run into the same problems about 3 times now and cannot figure out what is causing it. When we turn the hot water valve on, water begins to come out then stops abruptly. The only way to keep the hot water flowing is to open the valve up further. Then once we pull the diverter up for the shower to come on, half the water comes out of the spout and other half out of the shower. We are on our 3rd faucet so it has to be caused by something other than the faucet. All the other faucets in the house seem fine and water pressure seems to be normal. Any suggestions?