Hi Paul,
there is available a set of "Instruction Sheets" from the VOC Spares Company, but I guess if you have run a Norvin you may have a set already? These mention filing the ractchet, personally I am not convinced it is a solution. My Norvin was prone to jumping out of all its gears if it had the mind to, usually under hard load. Sometimes to be a cus when just cruising along in top. The "cure" has been a replacement camplate, but I got lucky here and found a good one second hand form a section member. The adjustment procedure is critical and fully detailed in Paul Richardsons book. Best advice is to join the club and get to section meetings where the fellow club members will have great fun telling you a dozen ways of fixing it. If you are lucky you may even find a member willing to lend you parts so that you can work thru them all until you isolate the offending article/s. This was the way Len Mathews helped me find a set of parts that would actually allow the box to go into the cases. True! Go in! Great bikes, great fun.
Oh we have a Norvin section now and if I am good they sometimes talk to me nicely...
Cheers
Jim Burgess (Norvin section organiser)
PS how about telling us all something about the real bike? The Norvin I mean of course.