Problem: Cab extender brackets coming loose from Freightliner Cascadia sleeper

My cab extenders, or rather the brackets that hold them, have started to come loose from the wall of the truck. The factory has fastened them with what I think is called "nutserts", threaded inserts that are pushed into holes in the wall. Then bolts secure the brackets to the nutserts. I dont think the nutsert is supposed to deform like a rivet would, it doesnt look that way, so I dont know what is supposed to hold it to the wall, glue maybe?

The problem is that in my case the whole has grewn (must have been due to vibration over the years) so the nutsert is no longer secured to the hole. The hole now has an oblong shape, like the digit 0 rather than the letter o and I can only assume they werent that shape from the factory. The hole is still 10 mm wide but is now taller.

Now, who knows the smartest way to repair this? They seem to be 10 mm nutserts with M6 threads, 19 mm deep. What if I order one size bigger, 5/8"? That is approximately 10% bigger according to my calculation.

Asking Freightliner is never of much help, they always refer to the local dealer, and the local dealer does not know.

 

I think they worked well 690 000 miles ago when their holes were smaller. (Thats what he said)