I only understand about half what you guys are discussing...but still enjoyable and educational.
One other fact may have some bearing on this. The company that manufactured the tractor was the developer and manufacturer of the Shop Smith line.
They used the best features and parts of other tractor makers. I have a parts cross reference. With their machine tool connection, they could have used exotic set screws or already had them on hand. Financial shenanigans and law suits caused production to end after 7 years.
Since they are so hard, what are my chances of chipping them out?