Your jumping second gear problem is a common one. There are many possible causes - worn gear dogs, worn shift drum, worn shift forks, worn bronze bushings, etc. You need to do some research on this website. Try the following link to see what's already been discussed:
https://www.google.com/search?client=sa ... XDGR2WrUuE
Lockers wrote:That's great - am I right in thinking that the CA77 parts book pretty much applies to the C72 as well? The pics in the parts book look really helpful.
Simon