1、 Turn off the main switch. Find the red and blue dots under your command. Buckle it with your hand to reveal a small hole.
2、 Use a flashlight to investigate the inside of the hole and see if one of the fixing screws inside is a cross or a straight hole. Use the corresponding screwdriver to loosen it.
The screw of a few brands has an inner square hole (such as Moen), which is more troublesome. When there is nothing available, be careful not to damage the screw opening when using other detachable substitutes.
3、 After loosening this screw, you can remove the handle. Sometimes the handle is pressed tightly, so you need to use a screwdriver to press against the lower edge and use a hammer to hit it up a few times to remove it.

4、 At this point, what you see is a large copper nut. After loosening the "apron" covering it, use a large wrench to open the nut and remove the valve core of the faucet.

5、 Investigate whether the copper surface under the valve core is uneven or has fine sand particles, and remove it clean.
Take out the rubber sealing ring on the flat surface and investigate for any damage.
6、 Generally speaking, cold and hot faucets have good overall integrity and high reliability in use. So, when you open it, you often can't find any obvious problems, and then you just need to replace the valve core.
7、 Finally, reverse the installation according to the above procedure. Note that when pressing the valve core, the two points below should be aligned with the two small holes in the faucet. The large copper nut should be tightened firmly with a handle, otherwise the gasket under the valve core will leak if it is not sealed with the faucet.
Article source: Flat disc faucet manufacturer www.baolonghs.com