Hi folks, trying to save a 110 that my neighbor had headed for the scrap heap.

The primary gear was missing teeth, tank was rusty, carb was plugged, tires were flat and the seat was shot. After getting all that sorted and cleaning the tank out this old thing runs fairly well.

My problem now is that it won't shift through the gears reliably, it will up shift easier than downshift.
when you get to 4th gear the only way to downshift it to turn it off and roll it backwards while lifting the shift lever.

I've looked at the shift stop lever and it seems to be ok, when I had the cover off I could see that the shift stop lever (arm with roller detent) would hang up on the peak of the gear wheel (star pattern deal) and would not rotate far enough to engage.
All springs look to be intact, although I'm not very familiar with these machines nothing is jumping out at me as being missing or broken.

any advise is welcome, thanks for keeping the site up!