Summary: the source of the call was low water volume on the hot side of a master bathroom Roman tub. The first diagnosis was to replace the cartridge. I also examined the water, pressure and thermal expansion in the home. The thermal expansion tank on the right side was full of water. The water pressure in the home was 70 psi. I also checked the water quality coming out of the bottom of the water heater, and it was extremely calcified. my diagnosis was to flush the water heaters, remove the sediment from them, and replace the cartridge. After looking at Moen’s website, I was able to find a cartridge that’s compatible with the existing cartridge. Upon trying to install it, it did not work. I tried removing the cartridge, shopvac through the hole where the cartridge was to remove any sediment, but that was unsuccessful. I then tried to very gently blow water through the hot side of the cartridge with the cartridge removed, and that also was unsuccessful. I then with the customer, though