I did not try the different circuit as don’t feel lie lugging it into another room. I did try a different outlet on same circuit that didn’t do anything either.
Highly unlikely to be a wall power problem. These things don’t generally draw enough current to see a significant voltage drop even through a really long extension cord.
I didn’t take apart the cover to check motor belt tightness or completely disassemble belt to check bearings.
Take the cover off and walk on the treadmill while watching the motor. if the motor keeps spinning when the treadmill belt stops moving…belt is too loose. If the motor stops, then check the belt tension, by pressing on it. It should deflect about 1/2 inch with a fairly strong force. If it is so tight that you can’t get it to deflect, try loosening it a little and see if that helps. But, the reality is that a loose belt is more likely to cause a problem than a over-tight belt.
If the bearing were the problem, I’d expect you would hear some ugly noises: grinding, scraping, whining, etc.
How would I tell motor controller? Eliminate all the other remaining possibilities?
If it is none of the above that leaves the MOTOR and the CONTROLLER. If the motor is going bad (windings have shorted), then it will draw a bunch of current under a small load. If the controller is going bad, it won’t draw very much current.
In my case, the controller board had a couple of diagnostic LEDs on the board itself. One for OVERCURRENT, and another for GATE voltage fault. For me the GATE VOLTAGE fault LED was illuminating but the OVERCURRENT LED was NOT. From that I was able to deduce that the controller was bad.
Given that I’m an electrical engineer, I was able to actually troubleshoot the board itself, and determine which component on the board was bad. I could read the part # and so I bought a few online and replaced it myself for about $7. I think the parts were $2 (at $0.50 each) and $5 shipping. I have 3 spares left.
However, treadmill doctor has parts for most treadmills made in the last 20 years, including controller boards. So, you can buy a board and simply replace the old one. Just costs more that $7 that way.