How can i fix tredmill?

I am troubleshooting a very similar problem. Incline works, console lights up like normal but when I press start, speed bolts straight up and then shuts itself down in about two seconds. I have tried to do all internet recommendations. I loosened and lubed the belt, blew out the motor & speed sensor, adjusted sensor to be as close as possible. Still no change in symptoms.
Now, do I start ordering parts or call the mobile repair guy? My treadmill is a Proform GI 400, model #831-29535.0 and when working it is perfect for me. I don't want or need to upgrade.

Hammons
March 2014