Thanks for the quick responses! Much appreciated to have other eyes on it.
If the female nut is spinning, can it be pulled out of its housing? Or pulled up enough to get some pliers in to grab it?
That's the problem...no, I cannot access it because everything is attached, ie, male bolt->tab from side trim-> female encased-in-tank nut, IOW no access to it.
You could try pushing down with mild pressure rather than lifting, pushing down might hold the female nut better by forcing down into its housing.
just tried that, no joy, still spinning underneath the tab, feels like little to no grip at all
I cannot loosen the bolt at all or in any way access the nut underneath the tab. It fits very well (German engineering, but gone awry). The tab is so flush to the tank that I can barely insert a single edge razor blade under the tab.
As a last resort you could Use a dremel to grind the top of the bolt and then glue the female brass nut in with epoxy or similar and the drill out the bolt. You would obviously have to source a new bolt
You mean grind away the head of the bolt completely, leaving the shaft inserted? I think I would rather cut a slot in the tab so I could then slide out the side trim, have the bolt head still attached and try to remove it and the recessed-in-the-tank female nut in one piece. I would have the head of the bolt to grab with a vice-grip or similar. I planned on re-seating it using epoxy, JB Weld, something like that. I feel pretty certain I could find a similar bolt, prob a hex head button cap bolt at a hardware store or Home Depot, Lowes etc. I do have a Dremel. On the Aprilia forum someone tried to Dremel or drill the head away and remarked how tough the material was.
Can you get a screwdriver, or better, a forked pry bar, between the panel and the tank, and pull the brass insert out of the tank with the panel? Then you could chuck it up in a vise and probably break the bolt loose.
It is really close fitting, a tiny flat blade screwdriver barely can get purchase...a razor blade is a very tight squeeze. The tank appears to be some sort of plastic, and risking damaging the tank is not something I want to risk by wedging something in and levering it.
I'm afraid cutting a slot and sliding the tab outward then addressing the bolt/fastener somehow may be the least damaging course????
This is what piece is spinning (from the other side) shown by the red arrow. The green lines on the other side, the offending side, shows where I would try to make the slotted cuts of the tab. I think thw side panel would still be very secure by putting a washer under the new bolt head, reinforcing the slotted tab.