Barefoot Spas Legacy Parts?

We bought our barefoot spa new in 1996. We use it for medical reasons, and we have not gone long at all without using it. We average about 3 times a week, sometimes much more. I was not expecting 25 years of longevity, but thankful to say we have it. I’ve replaced the headrests, the cover twice, and pump two went out last year. Other than that, this spa still works flawlessly. Does anyone know where I can get a replacement heater, or entire “motherboard” where you connect the wires for this old of a barefoot? I plan to continue getting use out of this thing, and I’ve read I may be on borrowed time with the heater (unit and coil). I’m worried I may not have access to legacy parts if I wait much longer to keep them in stock. Again, any ideas on where to find old, outdated parts for barefoot spas?