George,
I cut partial gear blanks to make the replacement quadrant for my F28. In my case, the issue was broken teeth. I do have a spare that you are welcome to for the cost of the post (from USA). As soon as I can get my hands on a scanner, I'll post a 1:1 plot that you can use to see if it is the same size. Took me a while to figure out where I stored this!
I extended the one side (bottom edge as seen here) so that the quadrant stays engaged when it hits the stop. Coming out of mesh and swinging free before hitting the stop seemed to be e design flaw that increased the impact. Since then (these were made over 25 years ago), my understanding is that one should not fit the kick start pedal beyond about the ten o'clock position. This to ensure you hit the ground before you run off the end of the quadrant I think is the theory. Prevent one form getting 'too much swing' as it were. If you look at the catalog pictures, it shows the kick start lever in a lower than expected position. So this bit might need trimming off.
Also, I seem to remember progressively thinning the tips of the first two teeth slightly to get the engagement to start more reliably. These teeth that I cut are standard involute 12 diametral pitch form, which is all that I had a cutter for. In reality, they might have used an extended addendum to make a more stubby tooth, with pointier tip. Certainly the later, coarser kick start gears are such a shape.
I had to make new shafts for the F28 and the A31, as they had problems with the conical splines. But the two parts I simple welded together. For the limited use foreseen (neither bike has gotten on the road yet!) I did not bother to heat treat the parts or use an alloy steel.
-Doug