@broadwaybabyto @bipolaron depending on the model you may not require central water shutoff (mine have local shutoffs to the fixture). Yes, leaving mechanical things alone for a while can definitely make them stick. You can always try turning it back and forth a lot, disassembling the easily removed bits, tapping it gently with a mallet…. But might just need a cartridge replacement. A long slow small drip with hard water can lead to a lot of mineral build up that can seize components.