I have a plan and a plastic welder I'm gonna try. Then goop and it on the outside and put the coupler on it.
If that doesn't work, i'll pull the vertical stack which is where the problem is and just put a new 18" pipe in. Probably 4-5' of pipe.
Have you once tried a plastic welder for repairing a pond? Can it be effective? I have been thinking about using this
one for welding.