Honestly, I thought all Hotsprings were able to be repaired no matter how old.
As far as a 2 part epoxy, Home Depot sells an epoxy putty that you break off a piece, mix it well and let it harden. As long as you mix it well and let it harden you may be pretty good. I probably would use it all around the fitting to reinforce it as well. If there are threads you might want to use pipe dope vs teflon tape not to put too much pressur on the plastic fitting, I don't know if you can use pipe dope on plastic though. If I get a,chanx l ce I'll post a,ling to the putty.