I have a proform treadmill that is currently driving me insane. A few months ago it stopped working intermittently. Basically when I switch the treadmill on it runs for a couple of seconds then stops, the console remains functioning and continues to run. I later discovered that if you start the treadmill at a higher speed 9kph plus it would run fine until you bought it down to a slow speed at which point it would stop again.
This has since become random and sometimes it will run at high speed sometimes not. but it will never run for more than 2 seconds at anything lower than say 6kph.
Sometimes i will get a 2 light blink code after it stops which apparently means that a wire has become disconnected from the controller board which makes no sense to me because when turn it off and on again, I can sometimes get the treadmill started again at high speed.
I've tried the following.
checked speed sensor placement
re-seated all wiring
loosened and tightened belt