1. Damage to Balls, Internal Raceway of Splined Nut, or Splined Shaft Raceway
Solution:
Clean the splined shaft raceway and inspect for damage.
If no damage is found, disassemble the nut:
Slip a hollow sleeve provided by the supplier (or self-manufacture one with an outer diameter slightly smaller than the splined shaft's minor diameter and an inner diameter slightly larger than the shaft end's outer diameter) over the shaft end.
Slowly unscrew the nut and inspect both ends of the ball return ring for damage.
If no damage is found, carefully remove the balls (not recommended for those without experience) and check the internal raceway of the nut.
2. Poor Lubrication or Impurities Inside the Nut
Solution:
Loosen and remove the dust seals at both ends of the nut.
Inject lubricating oil with a viscosity lower than ISO 32 (the lower, the better) into the nut's oil injection hole to clean it.
Move the nut back and forth within the effective stroke several times, then inject lubricating oil or grease with a viscosity between ISO 32 and 68, and reciprocate again.
3. Improper Installation
Solution:
Recheck and reinstall the parallelism between the ball spline and the guide, as well as the installation of bearings at the splined shaft ends and the concentricity of both bearing housings.
Straighten the splined shaft with a straightening machine.
