1. Before removing the piston, put a cloth on the knee to prevent the piston from falling to the ground.

2. Remove the lead from the piston.

3. Remove the top cover from the piston.

4. Turn over the horn and loosen the screw that fixes the terminal arm.

5. Insert a small wooden stick into the screw hole, and then gently tap the piston with a mallet until it falls out.

6. Wipe the piston with a clean lint-free cloth. If there is a lot of corrosion, it is best to soak the piston in kerosene or gas oil and wipe it clean.

7. Wrap your fingers with cloth and wipe the inner hole of the piston sleeve. Be sure to clean the piston sleeve thoroughly, and also clean other parts inside and outside the piston sleeve, including the place where the piston extends out of the sleeve and contacts the fixing screw, because it is easy to accumulate oil pollution here.

When disassembling the outer shaft and the piston, firstly unscrew the screw fixing the stop arm, insert a wooden stick or a copper stick into the screw hole, tap with a mallet until the outer bearing of the piston falls off, and then tap until the piston slips out. Do it where there is soft cloth. When the bearing is separated from the piston sleeve, do not damage the bearing due to falling.

8. After cleaning the piston and piston sleeve, you can reinstall it. Drop oil drops around the piston, and then put the piston into the piston sleeve.

9. Turn the piston from the bottom with your fingers, pay attention to the smoothness when turning, and listen carefully to the sound of friction. If everything is all right, oil the top of the piston and reinstall the outer bearing, so that the notch on the outer cover and the notch on the piston sleeve can be accurately aligned.

10. Place the empty spool on the outer bearing and tap the top of the spool with a mallet. The mallet must directly hit the center of the spool, because the outer bearing must be evenly matched with the top of the piston. Then turn the piston with your fingers again. If the piston rotates evenly and there is no resistance, the piston is clean. If the piston does not rotate smoothly at a certain point, you can put the valve core on the bearing and tap it gently at the point with resistance to balance the piston sleeve and the piston, thus producing uniform action.

1 1. Replace the piston cover outside the outer bearing, and then put the terminal arm on the shaft. Fill the gap between the terminal arm and the piston sleeve. The terminating arm may need to be tapped a little more to make it completely fit the shaft. When everything is finished, turn the piston again to make sure it moves smoothly.

Tighten the screws. The procedure of installing the string on the piston begins with the lever at the top of the piston. One end of the string is tied with a knot before passing through the small hole, then it is pulled down and wound on the rotating shaft, fixed at the end of the terminating arm with a small screw, and then wound on the other end of the rotating shaft. Then thread the string into the small hole at the bottom of the piston rod and tighten the bottom screw. Before tightening this screw, check whether the string is loose, but don't pull it too tightly, otherwise it will hinder the movement of the piston.