Hayward Super pumps are very different from the TriStar line. They will, usually, fill completely with water, though at lower speeds they sometimes look like a TriStar. No one should ever use glue to seal a fitting into a pump. If that is a pool/spa combo, it is very likely that standard PVC male adapter has shrunk from the heat of the water. They can also be damaged by the vibrations of a pump, especially if that fitting was re-used.
I would remove the union and the fitting, wrap at least 6 wraps of Teflon tape around the fitting after cleaning it off. Then, I always apply a thin layer of silicone sealant over that. When the fitting is removed, carefully look at it from the side. If the taper (male pipe fittings always have a taper) is very apparent, it is best to replace the fitting. More wraps of T tape would help but it won't last. A high-temp pump union is best. The threads on those is not tapered as they are designed to be threaded completely into the pump without damaging it and sealing with an O ring.