Sticky gear selector

First (and easy to access) suspect ,pawl spring  shape and clearance to pawl. . 

I would second Robert’s suggestion of the pawl spring. I recently rebuilt my Dommie’s AMC gearbox and when I put the outer cover on I couldn’t get any gears at all - the gear lever moved up and down by a couple of millimetres but wouldn’t select a gear.
To cure the problem I bent the upper leg of the pawl spring down slightly at the point where it touches the pawl so that there is a gap between the leg of the spring and the pawl. That gives you a bit of free play in the pawl (i.e. it can waggle up and down on its pivot with neither leg of the pawl spring touching it) AND the face of the pawl can move so that it is exactly parallel with the pawl spring plate. Once I’d done that, I got a perfect gear change.

Good luck.

Regards

Tony

As Tony describes, the pawl spring, when brand new, always needs adjusting - (I recall the books describing it as 'setting') otherwise it invariably has no clearance with the pawl itself and in this state will give either little or no gear selection.

Hopefully an easy 'fix'.

Symptom                                  -           Cause

Kickstart lever does not engage. -  Worn kickstart pawl

Kickstart engaging under load.  - Worn lay-shaft bearing or broken Lay-shaft

Cannot engage 1st and/or 4th gear  - Incorrect meshing of quadrant with the cam-plate

Engaging false neutrals  -  Incorrect meshing of quadrant with the cam-plate

Difficulty shifting between all gears.  -  Bent mainshaft

Gearbox will shift up but not down.  -  Return spring broken  

Gear lever will not return to mid position.  -  Broken return spring 

Poor gear selection  -  Gearbox selector spring reversed                  

Jumps out of 1st gear under load.  -  Worn engagement holes in lay-shaft 1st gear

Loss of 1st and/or 2nd gear.  -  Broken lay-shaft

Grinding noise in 1st gear under load.  -  Broken lay-shaft

Loss of 3rd and/or 4th gears.  -  Worn mainshaft bearing in inner cover

Whine in lower gears.  -  Worn bush in kickstart axle

Cannot engage neutral when bike is stopped.  -  Clutch needs cleaning and/or adjustment; or Incorrectly adjusted primary chain;

Loss of clearance between sprocket and gearbox shell  -  Sleeve gear bearing loose in gearbox shell

Grinding and/or chattering noise under load.  -  Broken gear tooth / teeth

Sloppy gear selection.  -  Too much mainshaft &/or lay-shaft end-float  or  Worn thrust washer (Lay-down only)

Cheers Phil loads of good info.