I think I am pretty close to figuring this out, but want to keep posting so if anyone else has this issue it will be well documented on here. Of course I am still hoping some of the gurus here stumble upon this post and lend their sage wisdom to help! I could be completely wrong below and would love to know.More Diagnosing:So I opened it up all the way down to the circuit board and got out my multimeter and here is what I find. When the hot tub is on and heating, I turn the Hot Tub "OFF" at the top side control panel I can distinctly hear first the heater relay click OPEN (as it should) and then in about 10 seconds I hear the pump relay click OPEN, makes sense. When I turn the hot tub back on I hear the clicks again in the reverse order, pump being brought online followed by heater, again all good. I then wanted to test voltage across my 240V heater when the tub is actually calling for heat and when it isn't and that is where things got interesting, here are my results:Tub calling for heat:Across heater terminals/legs (white and black) I get ~240 Volts and from each heater leg to the main ground or Neutral I get 120V. From research this is what should happen, it tells me the heater is running, which I already know.Tub set to "OFF": (I would assume board should cut basically all functions of the Hot Tub, definitely the heat)Across heater terminals/legs (white and black) I get ~6 Volts which slowly creeps upwards to about 9ish Volts over 3-4 minutes (BAD)From White heater leg to ground and neutral I get ~120 V (What is expected)From Black heater leg to ground and neutral I get ~112V (I am not big into electricals but I assume the missing 8V is what I am seeing when measuring between the legs)What I derive from all of the above is that even when the board thinks it has turned the heater off about 8v is leaking through to the heater which is slowly heating the water in the heat well. This inevitably trips the Hi Limit (albeit slowly as the 240V heater is only heating at roughly 8V). I can verify that the heater is still producing a small amount of heat over time as after about 5-10 minutes of the tub being in the OFF state, the heat well is getting rather hot. Lastly, I actually dipped the Hi Limit probe in a cup of very hot water and observed a safety trip while the tub was in the "OFF" condition. Upon tripping, voltage across heater legs went from ~9V to 0V, which is where it should have been all along once the tub stopped calling for heat.My best guess at repair, and please I really want feedback, is that the heater relay is possibly a bit corroded or weak and even when it clicks OPEN there is still some minor connection allowing voltage to slip through it. I am not well versed in electrical circuitry though, so this is all a hypothesis, would love someone with REAL knowledge to step in and let me know I got it and I should rip the board out and replace the relay. If there is another board defect to pinpoint other than the relay which is letting the voltage slip through to the heater I would love to know.It will take probably about an hour of time, $5-10 for the relay and another $30-50 to have the relay replaced, but that is nothing if it actually fixes the problem.