Turn off the water supply to the shower
Open the faucet to release any remaining water
Remove the handle screw and take off the handle
Remove the trim plate or escutcheon
Inspect the cartridge, stem, or valve assembly
Replace worn washers, O-rings, or seals
Replace the cartridge or stem if damaged
Clean mineral buildup from the valve parts
Apply plumber’s grease to moving parts if needed
Reassemble the faucet in the reverse order
Turn the water supply back on
Test the shower for leaks and proper operation