Sometimes OEM is the only way to go for perfect fitment. You should find wellnuts at a Lowes or Ace. One of those might fit just right. Ordering OE will probably take a few weeks for delivery.
I vote for "not deleting the post." Deleting is only for more extreme situations. You have about ten minutes to delete a comment but you can't delete a post unless you ask Cap to do that.
The real topic of this post might be "DO NOT ever, ever, EVER use thread locking agent on well nut screws. Unfortunate yet interesting that a steel screw stripped from this. Normally I'd expect the well nut to spin in the hole while the threads remained locked. That'd be a bigger problem. Tighten well nuts just snug, they won't come loose, do not use thread locker under any circumstances. Once you feel resistance while threading in, the rubber sleeve is getting pulled shorter top to bottom and expanding in the hole, you don't need much more tension that that. I can't remember ever having a wellnut screw fall out and I don't tighten much past where I feel the rubber getting squashed. The rubber maintains tension on the screw head and it probably absorbs a lot of vibration too.