(1) Check whether the upper and lower steel balls are reversed. Some models can be interchanged (e.g. CG, KC etc.) and some models can not be interchanged (e.g. SL200-8/SL150-4, SL125-30 etc.)
(2) Check whether the steel balls are reversed or not. The steel balls must be flexible with the axle-bowl track.
(3) Check whether the upper shaft bowl is missing.
In a certain gear, the gear retreats naturally without manipulation.
(1) Improper operation,like shifting improper.
(2) The claws are worn and the edges are rounded.
(3) Wear of shift cam and fork.
(4) Inappropriate assembly, resulting in inadequate gear engagement.
(1) Correct operation.
(2) Replacement of claws.
(3) Replacement of shifting cams and forks.
(4) Reassemble and readjust it.
Shift to the first gear, but have abnormal noise in engine and the motorcycle can not move, the motorcycle can only start in second gear.
Reason: Assembling the first-gear driven gear reversely.
Solution：Re-install the first-gear driven gear.
Starter rod is easy to push down and engine does not start.
(1) The edge of the starter block is ground into rounded corner.
(2) The top pin of the starter block can't bounce up.
(3) The first-order driving gear falls off
(1) Replacement of pawl block
(2) Replacing the top pin spring of the pawl block
(3) Re-install the driving gear.
After the boot rod is trampled down, it can not bounce back.
(1) Inadequate elasticity or breakage of start-up return spring.
(2) Over-tightening of the starting shaft with the side cover hole of the clutch.
(3) Start-up shaft deformation.
(1) Replacement of start-up return spring.
(2) Adjusting the matching position between the starting shaft and the side cover hole of the clutch.
(3) Replacement of starting axle.