Hot Springs Grandee - Electrical Issues?

[BobC]

I have a Hot Springs Grandee Spa - serial #G361028 that was built arong 1996. I have had to replace the small heater recirculating pump - most recently 2 years ago and when having the same problem this year - replaced the pump again. After following the instructions for attaching the old electrical cord to the new pump - as soon as I turn the spa on - the GFCI trips out. If I disconnect the plug for the heater - the pump runs fine - if I run the pump without water going through the pump - the GFCI does not trip out. I noticed when wiring the pump - the last person to replace the pump (a technician) did not follow the smae wiring scheme as the one supplied when I received the new pump. I have tried wiring the pump both ways with the same result - the GFCI trips out. I'm not sure if my problem is in the wiring? the GFCI circuit breaker, the heater or the controller? I am looking to try and find an electrical schematic for my spa but have not been successful. Any thoughts anyone might have would be greatly appreciated. THANKS