The Delta 1700 series faucets come in single-handle designs. These faucets mix hot and cold water using a cartridge inside the handle that opens and closes two valves, one for hot water and one for cold. The result, a perfect-temperature shower every time, at least until the valve seals crack and split. Once this happens, the only method of repair is a total overhaul of the faucet. Don't worry, it only takes 30 minutes to complete this job and no plumber is required.
Close the water valves to the shower or shut the home's main water lines.
Take off the Delta's faucet handle by removing the small screw holding the handle to the stem. This requires removal of the cap cover and an Allen wrench. Take off the knob and cover once the screw is removed.
Remove the handle assembly on the side of the faucet by unscrewing the longer screw inside the handle with an Allen wrench. You may need to remove the cap on the top of the handle to access this screw.
Take the bonnet, trim sleeve and O-ring off the faucet by sliding the trim sleeve off and turning the bonnet to the left by hand or with large, channel-locking pliers.
Pull the cartridge out of the faucet. The seat springs should come out with the faucet. If they do not, remove them with the tip of your screwdriver.
Push a new cartridge into place so the seat springs go into the shower valve holes inside the faucet head.
Reassemble the faucet by installing the parts your removed in reverse order.