Tank screw screwed - how to fix?

[Torque]

Drill and tap a bigger size, failing that if it's a through hole (I'm not sure without looking) you could put a longer bolt through and get a new nut on the back?

Oh right, that makes sense. Just longer bolt.
I will check if there is entrance from the other side for longer bolt. Yeah but now it's too dark
See you tommorow.