Hi Neil Greybeard,
You may remember my S/A gearbox problems detailed in "Gearbox Woes" on this forum. Been at it since January. I have the gearbox installed now. My original problem was I could select neutrals at ease. I took John (Chaterlea's) advice and tried to adjust the camplate plunger, but it was seized. Being reluctant to use heat under the bike, I took the gearbox out and dismantled it for a good bo-peep. I think 25 years of sitting around in our humid climate drew moisture into the oil-free gearbox and rusted the plunger adjuster. I did get the camplate plunger & spring replaced, and also found the claws severely worn. Otherwise the gearbox was in great condition.
I replaced the claw with a new one from Feked, and also the claw spring, but had the same problem as you with the lever not returning in 3rd & 4th.
I went through my spares, and found a claw in fairly good condition, and that solved the return problem. I was a bit puzzled, so had a closer look at the claws.
The new Feked claw was 5mm thick, presumably made from modern steel plate and certainly looks identical. The old claw was 4.75mm thick, which is 0.187 inches using my converter. This corresponds to 3/16". Whether this is enough to cause this problem is doubtful, but it worked. I did notice that in the "Gearbox Woes", another forum member also had problems and changed the claw from a new one to his old one, and also solved this problem. With the Feked claw, the tilting when changing gears was much more noticeable, but I could not see that affecting the gear change. I put it back together with the standard gaskets - one for inner and one for outer covers. On the bench, it seems OK but all a little bit stiff.
I am now waiting on new clutch nut and springs to get it back on the road, so cannot yet say how successful it has been. Hopefully it will get smooth with use.
Cheers
Col