help tighten gas tank

[Maynard]

99 vulcan 750....i have the service manual and attached a pic of the side bolts that mount to the frame.

the problem i am having is on the left side. i turn the bolt to tighten or loosen and it just spins away doing nothing. I can feel inside the frame and whatever the bolt is connected to is not spinning so even if i can get into this super small area with a wrench, there is nothing to hold on to that will allow me to tighten or loosen this bolt.

ideally i would like to tighten this thing up. But my thought was to take it apart to see if the rubber is still good. The problem is that i cant remove or tighten this bolt what so ever.

i dont even want to ride the bike with the amount of rattling i am hearing from the tank...its beyond annoying. The right side bolt seems tight enough and the 1 under the seat is fine also

any help would be great...thanks!