My tub/shower went from having normal hot water pressure to almost NO hot water. It trickles out of the tub faucet and barely comes out of the shower head. I have a Kohler Forte model single faucet. I've read that I should remove the handle plate and clean any debris, but I don't know how to get the plate off. Is this what I should do and, if so, how do I do it? Thanks for the help.