Root Cause
Platinum Member
5/8=.625Update, Sort of? I was able to get some bolts and get to the tractor today. 14mm is too small and goes in the hole without even touching, However 5/8 bolt seems to be about the right size and will try to start a thread but i did not force it for fear of cross threading. So here is my plan, I am going to get the paint out of the hole, gotta find a small enough wire brush or had thought of a dremel wire wheel also. while i am at it i am going to get a 5/8 fine thread bolt just in case and a 16mm 1.75 and 2.0 thread just in case. I am bound to be close if the 5/8 standard sae is trying to thread. It was late and didn't get to fool with it much this evening but i think i am making progress.
.625*25.4 =15.875 (most major diameter or outer diameter are a little small for clearance).
I think you are on the right track and another here warned about this type of overlap where even the pitch ALMOST fits.
If you have a bench grinder or Dremel, you can grind a cut into the first few threads imitating a tap. With the right bolt, this becomes an area for grime and paint to collect just like a tap does for chips. If you cut it right and leave the sharp edge on the left side of your cut, it can also help clean up some burrs as well.
Glad you are close. After 9 pages of posts, I think we are all invested in this now and need closure.