Belt not staying in the middle

Belt adjustments are on the back of the machine on either side on the rails. Loosen both off first to slide belt over towards center. Then tighten slightly. Run treadmill on lowest speed and adjust from side to side until belt stays centered. After it seems to stay centered run treadmill on high to see if it stays centered and make small adjustment until it does

Check the rocker arm on top

You have a defective touchscreen. It needs to be replaced.

sounds like a loose ignition wire to me

The belt does not need to be replaced more than likely. The problem is probably because that adjustment bolt is stripped out causing it loosen and keeping it over on that side. ProForm sells star washers that help them stay steady and not slip out. I would call them and ask for a couple of star washers and a new adjustment bolt for that left side.

there should be adjustment screws on the rear roller.
only adjust one of them (usually the left) if the belt rubs on the left turn the screw clockwise 1/4 turn and if the belt rubs on the right turn counterclockwise. Make small adjustments until the belt stays in the center

There is a round knob to the left of the steering wheel. This is a light switch. If it's turned to the left, the lights stay off. In the middle, the lights come on when the door is opened or the key is removed. To the right, it will turn the lights on anytime. By default, it should be in the middle (automatic) position. At the center of this switch is another knob that will pop-out if you push it. By turning the knob that pops out, it will change the intensity of your dash lights. Try popping the knob out and turning it all the way to the right. Then push it back in so nobody messes with it. Then make sure the light switch stays in the middle position. Hope this helps.

Adjust the tension on the right side rear using an allen wrench. Try 1/4 turn clockwise( should tighten). then run tread mill for 30 sec. to see if it centers itself. repeat again if not. if its to tight then turn the left side in a 1/4 turn

speed the belt up to around 4mph while adjusting the belt. you will see it centre very quickly. once centered leave it to run for a couple of minutes to see if it stays central.

You don't mention replacing any tensioner bearing which if worn could be causing the belt to drift.
I would probably remove any covers and physically watch the belt to try to determine which of the surfaces on which the belt runs is at fault. I think the belt is probably not that cheap so I hope you cure this soon.