I am having problems with both the cold and hot water supply valves to the bathtub. The cold water supply valve is fine when the valve is either open or closed, but leaks every time I turn it one way or the other. Which means I have to have a handy supply of paper towels every time I want to turn the water off. Is this a leak in the valve itself, a water supply problem, or something else?

The hot water supply valve was working fine, but I recently re-seated the hot water faucet which was leaking. When I turned the supply valve back on the water pressure was down to a tiny dribble. The hot water in the bathroom sink, which is on the same supply line, is fine. So I am wondering if there is a problem with the supply valve. Perhaps it isn't turning all the way on and I need to repair it?

Thanks for any advice?

JK