Me again :lol:
Good answers all. A quick attack with a hacksaw blade sorted it. Cover off, find TDC on the comp stroke, timing marks lined up, no tension in cam chain / valve gear, clutch off, kickstart shaft out.
At this point I followed advise given by others to remove the shaft and gear together as this keeps the ratchet pawl secure in its place. Swapped the mini spring and pawl to the new shaft and slid the gear back onto the shaft and pawl.
Again as directed by others I found it helpful to keep them assembled with the big spring as I put the new shaft back in. The tricks to getting it all in seem to be two fold.
First I struggled a little to get the hooked end of the spring past the gear teeth inside the gearbox. I got over this by removing the spring and practicing the right angle for insertion without the shaft in the way. After getting a feel for it I put the spring back on the shaft and it went right in with a wiggle.
Second the shaft needed to be turned (using the kick lever for leverage; really!) clockwise while pushing the shaft and gear in together. It all clicked together and the lever is returned to the top.
Tried the kick action a few times and all was smooth; RESULT!
Put the clutch basket back on paying very close attention to the timing marks on the crank and intermediate gears.
I'll post gallery pics later.
Meanwhile; a quick question. The clutch center nut was little more than finger tight on the way off (but tab washered). The 05 manual I have says 120nm / 88 foot pounds torque and this seems reasonable. No reason not to use this torque is there?