several IPL for mtd riders show the bolt for the bottom of steering shaft as 710-1309.
one says Hex Patch Bolt 5/16-18 x .62
another Torx Bolt 5/16-18 x .63" Lg.
and a part lookup shows as Screw-pan head . this latter being what's like in my hand with a large philips drive.
I always have to use a large bit and hand impact to remove them.
Any idea why MTD used pan head. there is a cap washer above it.
Usually I replace with a simple hex head.