the nut appears to be some sort of insert nut that looks pressed in?
So what is the solution?
I tried to jam a nut in place with the OEM recessed allen head bolt.. first ride out it fell out (yeah it was loctited...)
now revisited it, there seems to need a bush to fill the frame to reduce the amount of slop...
I still have no idea what type of nut to use.. I tried liquid metal to "glue" a nut in place that I tapered with a grinder.. and it fell out...... I can't be the first to have this problem..