These seem to be commonly needed parts that are not available any more. #11 is the shift drum stopper and 15 is the neutral stopper.
I decided to see if I could repair the ones from my spare engine cases.
The axles that the 2 rollers ride on wear out and cause the rollers to be off center causing shifting problems. Here's what worn out ones look like. Notice how the roller are not centered.
I drilled out the riveted ends of both rollers and used a small punch to drive out the axles. This is the shift drum stopper and you can see the wear on the axle. The ID of the roller is perfect, very hard material.
This is the axle from the neutral one.
For the shift drum I measured the ID of the roller at .277". I found a 8mm bolt with a shaft size slightly larger and chucked it in the drill press and used a file to remove the flats of the head and remove material from the shaft until it measured .275".
Then I ground down the length until the shaft was .005" longer than the thickness of the roller.
I center punched the center of the shaft.
Then I drilled a 9/64" hole and tapped it with 8-32 machine screw threads for a machine screw.
Here's the finished product.
I had a little interference with the bearing for the shift drum so I had to grind a bit more off the head of the bolt to provide clearance.
It finished up like this.
The neutral stopper was similar but I used a 6mm bolt, it was the perfect size for the ID of the roller.
Also tapped for a 8-32 machine screw.
The 8-32 machine screw is the perfect size to pass through the hole in both levers with no slop, it's a slight interference fit. Here they are test fitted in the case for the final time. I didn't put the springs on for the test fit.
Some blue loctite on the threads and jam nuts installed so the screws will not come loose. Here they are ready to be installed.