OK guys I'm not sure if I've done right, but I inserted the gear change and believe I now have it in neutral. Looking at the two marks, they seem to be almost in-line. Now I've read on another thread about a number of rogue quadrants and it's possible to change the index position by one tooth to get the marks to the align exactly. As my gearbox is a late one 1962, do you know if the rogue quadrants were around at that time?
The reason for removing the front cover was because gear selection was difficult, changing up was OK but changing down was a lottery. It seemed like the gear lever wouldn't return to it's central position, so I suspected the return spring. Just now without the front cover on, the selection was much easier and positive.
I have never dabbled with Pre-unit gearboxes, only Unit ones, so I'm a bit of a novice. Sorry about that BSA Singles a piece of cake, this one I'm on a learning curve and I need some guidance