Plastic weld is the way to go.
The only problem (compared to other plastic repairs) is the thickness of the argo tub. The plastic is so thick, it’s hard to get enough heat into it to weld reliably. And once you get enough heat into it, it takes a fairly long time for it too cool enough to where you can leave it unsupported (ie: won’t sag or move).
Certainly the best way to go, but it takes a fair bit of practice to get it to work the way you want.
When I modified mine for the front grill, I took scrap pieces and cut them into very thin strips. Then I used those as the filler rods for welding. That way, I didn’t have to worry about using the wrong filler rod with the tub.
Good luck welding ‘er back up.
