In our renovation of our church pool we replaced almost all plumbing except what is inside the gunite. We've still got a few drips to fix. A friend with 40 years pool experience told me to crush a piece of PVC with a hammer into very small pieces and let the pieces soak in an ounce or two of pipe cleaner. Make sure the cleaner is primarily methyl ethyl keotone (all PVC goops seem to have this in them). The MEK will dissolve the pieces into what is basically liquid PVC. Then take something like a popiscle stick and apply the stuff to your leaky area. I haven't had time to use this method yet but he hasn't steered me wrong yet. I'll report back after the repair.
Hal