So it turns out a number of problems with my KS mechinism, some relevant to jamming and others not, and finally solved.
1) Ratchet gear 67-3376: My actual ratchet-gear teeth are really worn down by like a millimetre. They look rough and slightly mashed about. I thought this would prove very relevant.
2) The ratchet bronze bush 67-3169 had a lot of play both on the mainshaft and between it an the ratchet. Talking of a combined 8 thou or so.
3) The Main KS steel bush in the outer cover, a b@tch to remove involving a stout press with simultaneous heat, also had significant play on the KS shaft. It's ID should be a thou max over of the KS shaft whose factory dimensions are 0.7455~.7500, It had about 10 thou play.
3) The least play was in the blind KS smaller bush, nominal ID 0.561~563. This was about 4 thou over, but being I did not have the correct blind bush puller, I decided to deal; with items 2 & 3, whilst awaiting a new ratchet gear from UK. Assembly with new KS large bush and new ratchet pinion sleeve bush might prove the problem was solved.
This proved the following:
1) My clapped out ratchet pinion teeth, though they looked bad, did not matter.
2) Nor did the small inner kick start quadrant steel bush.
All that needed changing was the ratchet bronze bush 67-3169 and the large steel KS bush 67-3153. In fact I had custom ones made then lapped and honed them manually to close tolerances on the quadrant shaft and mainshaft and between pinion and OD of the bronze bush.
It would seem these are the two key components to carefully blueprint, and the major cause behind KS jams.