Well SWINE , you were dead on with the check valve. After my voltage testing I decided to look at the check vale on the suction side of the circ pump again , this time in the daylight . What I found was the rubber broken complety off the plastic and cutting the flow off to the pump almost entirely. So , that is my problem without a doubt as far as tripping the heater high limit switch !
I also found a check valve going to or coming from a set of jets that has the nipple broken off , I suspect that is why a few of my jets were not working. There is no water leak here so I guess the valve did its job.
Now I need to find these two check valves and I should be in business.
Thanks again for steering this spa newbie in the right direction.

EDIT: yay!


Well done. If you're ever looking for work, I'm hiring!