Thanks to "Swine" I was able to get the spa running! It started to heat up but tripped the hi-limit reset on the control box after a few hours? The spa hasn't been run in a year or so. Is there a way to test the hi limit reset button. Could it be defective too sensitive?

Thanks

If the heater's not actually overheating- replace the high limit.

You can test it by first turning off the power, filling up a cup with hot water, and placing the hi-limit bulb into the hot water. It should trip around 115-120F. If it's tripping much sooner, it's bad.