Sea-doo gtx 260 is seat assembly

[dvhouten]

I am trying to replace the expansion nut that holds the lateral arm (3 on the diagram) that the seat swivels on. It is connected to the body with this expansion nut.

Expansion Nut M6 X 1 250100083 250100150 (23 on the diagram)

Here is the blowup diagram: https://www.seadoopartsnation.com/oemparts/a/sea/500d580af870020908257569/seat

It won't unscrew probably because the nut is spinning. Is there a way to stop it from spinning or can I just force it out since it seems loose anyway.
TIA,
David

 

[ski-d00]

You have to reach around and hold it with a wrench, then not drop the nut and washer.

 

[dvhouten]

You have to reach around and hold it with a wrench, then not drop the nut and washer.

I know that would seem to be the simple solution, but to get to the nut, you'd have to disassemble the entire top of the is260(and that's a huge task). It's not really a nut per se, but a compression plug that expands and stays in the hole when you tighten it.
It's a little loose and I might be able to pull it out, but I'd hate to crack the housing in the process. It's not loose enough to get even a pair of needle nose behind the cap to hold it while I loosen the bolt.
I might just assembly it as is and wait until a need arises to pull the top off again.
Thanks,
David