Hello
Recently my daughter and her husband gave my wife and i their hot springs sovereign hot tub model I. when we set it all up and got ready to use it, it would keep blowing the gfi. We narrowed it down to the heater curculation pump. The casing of the pump is cracked and I think that maybe when the water starts going through it it causes a short, as we have had the cover off the fan end and it will spin for a minute or two and then pop the gfi. Must I replace this pump, or can I possibly use some kind of water resistant caulk.
I know nothing about hot tubs.

replacement definetely
however - rule out the heater itself first before buying a pump - disconect heater wires/connector and try again - may not be the pump causing the problem although it sounds like the pump needs to go anyway