Recently bought a house, built in 2006, and I've found the MBR shower doesn't have any hot water, so I got a replacement cartridge (a Gerber 95-154) and figured that would fix the problem, but it didn't. So I removed the escutcheon cover plate and happily found it had hot/cold shut off valves in each arm which allowed me to remove the cartridge and check the hot water side, i.e., I set the screw for the hot water valve fully out (on) and fully in for the cold water valve (off), and didn't get even a drip of hot water out of the valve body face. BTW, I do get very nice hot water at the garden tub located right near the shower, so I know we have a working hot water heater. So my question is why, does this indicate a bad valve body? Is there anything serviceable in the valve body, I see a plastic white insert that the balancing cartridge mates to but don't know if it's removable or not, or if they get clogged and need to be cleaned. I suppose the other possibility is the hot water shut off valve is stuck closed, and there I see a large nut around the adjustment screw, could I remove the large nut and inspect the valve (after shutting off the main of course). I guess if I could remove the hot water shut off valve I could at least verify hot water in the pipes, and if there is something clogging it I could perhaps drain it out. Anyway, looking for ideas and hoping an expert will take pity on me! Thanks.

Solved the problem, found the balancing cartridge in the valve body was frozen due to hard water deposits. After soaking in white vinager for a few minutes it unfroze and moved freely, then reinstalled and now I have hot water with very good flow, and the best part is it was basically a free repair since a simple cleaning of the old part fixed it.

You apparently did not give us enough information, such as the make and model of the faucet, beucause most balancing units are part of the cartridge or blow out if the cartridge is removed, which you stated you had done, and the water is turned on to test the flow.