Our 8 year old kitchen faucet (Moen) recently started humming loudly when the hot water was turned on, but only at a certain fairly low rate of flow and only when the hot water has arrived at the faucet. Then the cold water will cause the same humming at the same rate of flow. It sounds like its coming from the faucet, or perhaps the supply tube under the sink. I assume it has something to do with thermal expansion. I changed the Moen cartridge. I insulated the hot water supply tube. I drained the entire water system to restore the air cushion. Nothing helped. Do I need to replace the faucet or supply tube? Is there something else that might work?