A round disc of hardwood with a turned taper on the inside. Then longer mounting bolts. Or as mentioned, repair it. Get a Fiberglas repair kit at Walmart. Rough up the plastic and wrap it with resin impregnated cloth.
Here's an epoxy repair of a plastic radiator neck done with copper pipe the right size to fit the hose ID. I soldered a piece of wire around it to help with the connection. It's been working for 20 years.
Joe, even multiple wraps of electricians tape might work if you can pull the two fractured surfaces together. As suggested, a hose clamp would help with that. As I'm sure you know, electricians tape stretches slightly which makes it great for this type of repair. Since only air is passing through the hose, a water-tight seal is not necessary. If it was, that tape they advertise on TV for sealing boats, aquariums, etc. actually works quite well. Don't remember the brand, but Amazon carries a variety of look-a-likes. Good luck. Jim
I would call it a vacuum hose flange, its not a plumbing flange, though you might be able to make one of those using one if you have a lathe.
I would try to fix it as the other guys have outlined. Hose clamp, or even wire wrapped then epoxied would probably be better than new - that plastic wall was too thin for the stress, clearly. I've seen the same with a motor bearing pocket if you can believe it
If that flange thing is made of PVC, you can fix it with PVC cement from your hardware store. Check the plumbing supply department. I repaired a huge break on my old motorcycle fairing with it.
They also carry one with a 2" i.d. The best strategy is to carry the part that needs to fit it to your nearest Woodcraft (or Rockler, or Klingspor) store. They all carry a wide range of dust collector adaptors. Another place to search is the plumbing department at your local orange or blue borg.
But, as Dick Cours suggests, I think I would try to turn one to fit, since that would be the most fun solution to the problem.
Looks like PVC or ABS. Plast Aid is a possibility, see link below. This is great stuff, that I've used to repair components in our old hot tub - it extended the tub's life for several years, until an irreplaceable part failed.
Plast Aid will give you slightly longer working time than PVC or ABS cement to put a hose clamp around the fitting and tighten it up, so it's the same size it originally was; but only slightly. You want everything ready to go, and you want your blood caffeine/adrenaline levels good and high. It heats up when it cures, and the heat accelerates the cure; so, if you mix large quantities, it will cure faster than you can work it. It can be both an adhesive and a molding compound, so I'd mix up just enough to put into the crack, then clamp it shut and let it cure (put some vaseline or the like on the clamp to serve as a release agent, so it doesn't stick to the Plast Aid). Remove the clamp and mix up some more to build up on the outside, across the crack.
If the hose is still coming out, because the fitting is no longer quite the same size, you could probably use some Plast Aid to skim coat the inside to make it a little smaller, although duct tape could do the same with less drama.
It's a neat little company. When I called a couple of years back, when dealing with the hot tub, customer service was the company owner, and his young granddaughter was visiting, so I could hear her in the background, talking to herself as she played with something. And he, the company owner, knows his product really well, and is happy to give guidance.
Your hardware store may have it. Or a hot tub service/parts house, or a plumbing supply house. Or call the company to get suggestions on sources.
Joe Am I wrong is that the same size as a shop vac inlet, if so I have a couple of them just laying around if you want to try one just let me know. Larry