I have recently lost the amount of hot water in my upstairs shower. I still get lukewarm water but not hot water. The upstairs bathroom sink still gets the hot water, as do all other faucets in my house. The water pressure has not changed. The faucet is a Symmons Allura S-76-2. I have read other posts on this topic, but I'm hoping you can help me given my specific faucet model.