Warped Korg 707 case

I got this nice Korg 707. Back in the 80s I really wanted this digital synth. I have unstuck all the switches and cleaned it up.
There’s one issue I can’t fix. The seam in the back of the plastic body where the upper and lower halves meet is open. It looks like this was in a hot storage shed or something and the plastic is warped.
Is there any way to fix this? I can’t think of any that don’t involve drilling holes for more screws or gluing it permanently shut.

If its had a few years to misshapen itself, it may be too late. At best you will need to clamp the shell in a mold to straighten it out, then heat it via boiling water or a uniform hot air setup.

That’s what I was thinking. Thanks!