Came across a worrying snag with this 'box. I found it wouldn't change into any gears other than 1st and neutral!
A lot of fiddling and a farting about later (I was still learning about how this 5 speed is put together), I managed to get the gear cluster out. I could see no wear or damage at all, everything inside was pristine clean. The gears slid nicely on their shafts and the selector forks lookedperfect. Yet every time I reassembled it in the case, the cam plate would not rotate.
With everything apart again (about ten times) I discovered that the pins on the selector forks (they slide in the tracks on the plate) seemed to sit very tightly in certain positions. I pulled everything apart again and inspected the cam plate. It's made of hardened steel and the main surfaces are ground flat. The tracks look like they are stamped out when the plate is manufactured and judging by their surfaces, nothing further is done to them to clean them up before or after the hardening and grinding processes are carried out. The inside faces of the tracks seemed a little rough in places and the edges very slightly burred, from the subsequent grinding process.
I took a fine needle file and some emery cloth to the plate and carefully cleaned up the rough edges (it was hard work, that plate is very hard steel).
I put it all back together one last time and finally found that I could get all 5 gears, as advertised.
I suspect this gearbox might have been removed from a new bike and changed under warranty very soon after it went on the road, because I don't see that it can ever have worked properly. That would explain its pristine condition.
Anyway, it works now. My DIY right side conversion is now all fathomed out and mainly sorted.
I need to have the outer case milled out with a 20mm round hole to allow the gear selector rod go through. I've ordered a 14 x 20 x 12mm sintered bronze bush and associated oil seal for the modified shaft and a bearing end cap to seal the original aperture in the rear side of the main casing. I've left enough of the original shaft in place to allow it to be supported at both ends, in both cases - unlike the factory one, which appears to rely only on single sided support.