1. Injection method: use an ordinary syringe to extract anhydrous alcohol, inject it at the seam of bad key position, and keep pressing the key to enhance the cleaning effect. This method is simple and practical, especially for the keys distributed around the keyboard.

2. Shaping method: weld the three legs of the faulty key with a tin sucker, remove the key cap, the support rod, the elastic sheet and the return spring, and pull out the microswitch. It can be found that the shrapnel is concave or flat, pry it up with a fine needle to form a convex surface, and gently toggle the internal switch to the appropriate position with a small screwdriver. Finally, it can be assembled in the reverse order of disassembly.

3. Immersion method: This method is to disassemble the faulty key, and you can see the moving contact made up of two small metal sheets. Use tweezers to repeatedly wipe a small alcohol cotton on the contact sheets until the metal shines, and finally reassemble it.