On the sprag clutch/post type motors that had the band brake around the flywheel, kill switch setup, commonly fitted to MTD's etc, there was a metal tab that bolted to that post below the thread for the tank with a short 1/4" counter sunk screw. It had a hole for the tank bolt to go through and poked up to flywheel height.
Then the spacer collar was the width of it shorter than a normal one.
I will see if I can get a picture, of the tab, I'm sure I've kept one.
My solution would be get a short bit of steel. Drill a hole and tap a 5/16 thread into it. (or you could file down the post so you could weld a 5/16 nut on the back and have it sit in the right spot.
Then carefully drill two holes below it into the lower part of the post. Tap them and screw in two short bolts.
Trim down the spacer or the built in spacer bit if its a vertical pull starter.
Should last forever.
Bob.
