Repair steps of faucet:
Step 1: Close the inlet valve. Remove the small screw on or behind the faucet handle to remove the handle fixed on the faucet body. Some screws are hidden under metal buttons, plastic buttons, or plastic sheets, which snap into or screw into the handle. As long as you turn the button open, you will see the handle screw on the top. If necessary, use some penetrating lubricant like WD-40 to loosen the screws.
Step 2: Remove the handle and check the parts of the faucet. Use large slip joint pliers or an adjustable wrench to remove the packing nut, being careful not to scratch the metal. Turn the spool or shaft in the same direction as when you turned on the faucet to unscrew them.
Step 3: Remove the screws holding the washer. If necessary, use penetrating lubricant to loosen the screws. Check the screws and spool and replace them if they are damaged.
Step 4: Replace the old washer with an identical new washer. A new gasket that exactly matches the old gasket can usually keep the tap from dripping. You should also notice that the old washer has a bevel and is still flat, and replace it with the same new washer. The gasket designed only for cold water will swell sharply when hot water flows through and block the water outlet, making the flow of hot water slow. Some gaskets can work in both hot and cold water, but you have to be sure that the gasket you buy for replacement is exactly the same as the original one.
Step 5: Fix the new gasket to the valve core, and then reinstall the parts in the faucet. Rotate the spool clockwise. After the spool is in place, install the packing nut from the beginning. Be careful not to scratch the metal with the wrench.
Step 6: Reinstall the handle from the beginning and put the button or disc back. Open the water supply from the beginning and check for leaks.