Thanks Steve, it is a brushless motor. I checked all the trims on the radio and they were all set to neutral. It's kind of a funky design, there's a battle switch to turn the pump on, but when it worked it would also turn on apon pressing a stick on the controller, so the pump isn't running all the time. With the battle switch on, it would run all the time. I'd like to check the voltage coming out of the pump esc, but you mentioned it's difficult? I'm pretty handy with a voltmeter, what are the steps involved?