I have a 4 year old Leisure Bay Genius Series LB104 240V spa that has started tripping the 50amp breaker. This happens with both of the 2 pumps running and the breaker will not reset and does not feel hot. I replaced the breaker and it still does not reset. I removed the side cover to the spa and tightened all connections. I found that if I disconnect pump number one from the control panel, everything works and the breaker will reset. I also tried plugging this pump number one into the input for pump number two, and again, it trips the breaker. Does this mean that the pump is bad, if so where can I get a replacement that will work. Or, could it be something else?

Pumps are fairly easy to come across, but your problem will more than likely end up being you heater, you may want to disconnect the two wires leading to the heater and then try running the pumps. If the pump 1 still trips the breaker then you will need to replace the pump.
http://spapartsnet.com/category-Pumps-main.html