We have what looks a lot like a T675 single lever rotating shower valve, fairly old. We're having problems with water pressure when we turn it to hot, and are trying to remove the valve to fix it, but can not get it off! We see a small hole underneath the valve but no screw or anything. What should we do?

You've giver me a model number but not a brand name of the shower valve. This "small hole", Is it located under the handle? Back to you, Tom

Yea its an american standard, and the hole is under the handle

OK Gotrcha! There's a Allen Head Set Screw in the handle that must be removed before the valve can be opened up. Here's a drawing that may help. (see image) good luck, Tom