Starting from last week, the hot water coming out the bath shower became colder. Looks it is the hot water is losing pressure. The make of my shower is EMCO. Anybody can tell me how repair it? Thaaaaa... nks!

Shut the water off to the valve and open it up. Check the seat or cartridge inlet ports for trash and while the valve's open turn the water on for a minute to flush out the valve body and supplies. Good luck, Tom