I also have a blinking red light issue. I have a Hot Springs Jetsetter-JQ. It's probably over 10 years old. I got it in 2007. I've had no problems until this month. It started with the spa getting into the blinking red light mode intermittently. I replaced the water and put in brand new filters. That did not fix the problem. I talked to my local dealer earlier this week. He suggested that my circulation pump may be starting to go bad. I left the system in the blinking red light state until today where I could look behind the panel in daylight. The first thing that I did today was to reset the GFI to reset the heater high limit thermostat, and discovered a brand new symptom. Now the red light starts to blink immediately (within 2 seconds). Before today, it would stay lit for at least a minute or two - sometimes for days. The second thing that I did was remove the cover from the Q2000 control unit and checked voltages (ps. configured for 120v). Power is going to the circulation pump, but nothing else. The third thing I that I did was tap on the circulation pump, and it did start making a chirping noise and I saw a slight water disturbance, so I do believe my silent-flo pump is indeed going bad. But I don't think that explains why the red power light now blinks immediately upon power. I also tried disconnecting the control panel power leads that goes to the heater (no-fault 6000), but with no effect. I'm not sure what to do next; in reading above it sounds like my thermistor might now be bad. Is that a component on the main circuit board?