See if you can get hold of some Ethyl-Acetate (chemist), it's a solvent for ABS and will weld it together.

Try on a spot out of sight if it solves your plastic and make a test weld.

Don't spill it on the rest of the hull.

I use it on all ABS joints and it works very well, nothing ever comes loose again.

Let it air out completely, otherwise you'll end up with weak spots.(don't ask...)

Regards, Jan.