1. The coaxiality of the piston and the piston rod should be adjusted.
2. The machining accuracy of the inner wall of the hydraulic cylinder and the surface of the piston rod should be adjusted within a proper range.
3. If it is caused by the material of the seal, just replace it.
4. Add an exhaust device to the hydraulic cylinder to remove air.
5. The clearance between the piston and cylinder body, piston rod and guide sleeve in the hydraulic cylinder should be adjusted.
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