GB gearbox problems

[TonyBaxter]

Hi all, I'm having what I think are not unusual issues with my GB 'box on my '57 NH. Sometimes sticking, and then sometimes slipping on the ratchet. (I haven't actually had the bike running yet, it is only just back on two wheels today, just want to get the issues fixed one by one).
Both the kickstart ratchet pinion and the driving ratchet have less than perfect teeth, definitely some light wear/damage. But, the teeth aren't rounded off at all. The pinion slips nicely on the pinion bush, but the bush isn't coming off the shaft, I assumed it would be a sliding fit, thoughts? And is there a figure for the length of the spring behind the pinion, perhaps that isn't pushing hard enough?
The actual kickstart quadrant looks fine.
I know from searching other posts that apparently the gearbox can give problems if things aren't just so. I wanted to ask before I contact Geoff and get an order in, just in case I'm missing something.
Cheers.