We have a Kohler wide spread faucet that is leaking under the escutcheon on the cold water side when the hot water is on but the cold water is off. The water does not appear to be going into the cabinet just bubbling up under the trim and running into the sink. When the water is turned off the leak stops. Each handle has its own valve body. Threaded flexible hoses connect each handle to the faucet at a T. Where do I start trying to debug this? Is the T clogged? Is it a bad valve in the cold faucet? The hot side is almost always the one that is used and the cold side in not frequently turned on. The faucet is about 14 years old. We do have hard water.