Belt moves to one side

Their is now way to adjust the pulley it runs on a bearing if the pulley is wobbleing you need to replace the bearing or get a new pump .
If you are talking about the belt then their is a belt tenisiner that is a ware part and needs to be replaced from time to time not that expensive .
If you are talking about steering wheel play side to side there is an adjustment on the top of the steering box that can be tightened to reduce the play .However the problem may be with worn front end parts

There are two holes on each side of the back covers of the treadmill. They have the adjustment bolts in them for the rear roller and It will require an Allen wrench to adjust it. If you tighten one of the bolts it causes the belt to move away from that side. So if it's the left side of the belt that's moving close to the rail then tighten the left side and vise versa for right. Turn the unit on and set the speed to about 3. Tighten the side that the belt closer to the side rail about a quarter turn. Be patient and give it a minute to settle after you adjust it. Repeat until the belt has moved back to center. If it moves too far just back it off a bit.

If you mean the belt is riding off one of the pulleys, the usual reason is one of the pulleys is not aligned with the others.

Hey Joe, at the back of the treadmill, you have the rear roller. The roller has a tension screw in both sides that are the adjusters as well. As you tighten the right side it will force the belt to the left, and vice versa. I turn the walk belt on to speed two, be carefull the belt will be moving. Slowly adjust one side and watch the belt move, then the other side until it centers. Shut it off, the belt should lift from the middle no more than two inches with a firm lifting force. That's it. You might need to tweek it to keep it centered.

Hope this helps, Matt

If you need further help, I’m available over the phone at https://www.6ya.com/expert/matt_8dbc24bf722649ac

There are Allen bolts on both sides of the bottom on the front (away from the console) of the treadmill. Turn one one way and the other the other way to adjust the belt. If this does not work, your belt is probably worn and stretched and needs to be replaced. See Treadmill Parts to order a new one.

On both ends of one of the rollers are adjustment or takeup screws. You may need a screwdriver or open end or allen wrench to adjust them. If the belt is moving toward the right, adjust the right side of the rollers to be farther apart (if I'm not mistaken). This should cause the belt to walk to the left. Run the machine and watch for belt movement. If the belt is tightening too much, adjust the left side to make the rollers closer together. These adjustments are best made while the belt is running, but BE CAREFUL!
Gary

At the back of the treadmill, there are 2 adjustment screws, 1 on each side. They are used to move each end of the rear roller either forwards or backwards. I typically teach people to use the left hand adjustment screw because the direction you turn the screw is the direction the treadbelt will move. Turn the machine on and run it at the lowest speed, usually .5mph and while it's running, make an slight adjustment. If it's running while you do it, you will be able to watch the progress of the belt and it's easier to fine tune it this way. Using an allen key (you should have been supplied one with the machine) turn the adjustment bolt a 1/4 turn in the direction you want the belt to go (only from the left). Wait a few minutes and watch it carefully, you do not want it to run up against the side rails of the machine, this will shred the sides of the belt. You really shouldn't need to turn it more than a 1/4-1/2 turn to make an adjustment. Watch the belt migrate back towards the center and when it gets close, turn the screw slightly back a bit to stop the progress, or it will stop on it's own as it reaches the higher angle of the roller. Patience is key here, don't try to do it one morning on your way out to work. Give yourself 15-20min to focus on it and remember that as long as you don't use large adjustment increments and pay attention to where the belt is headed, you'll be fine.

To adjust the belt: Less Belt Tension: turn both adjustment bolts on back of treadmill in a counter-clockwise direction. More Belt Tension: Turn both adjustment bolts equally in a clockwise direction. Center Adjustment (moves belt center to the left): Turn left-side adjustment bolt counter-clockwise. Center Adjustment (moves belt center to the right): Turn the left-side adjustment bolt clockwise.
An over tightened walking belt can raise the amp draw of your treadmill, contribute to seam separation on the walking belt, or both, so do not over tighten the walking belt.
You should be able to lift the belt in the center on the side by approximately 2” to 3”, if you cannot lift it by 2” to 3”, the belt is too tight.

there is a knob that moves the front roller [rotates] the roller side to side to center a moving belt - the grit belt. the roller has a slight bevel from the center out to the edge. both edges. use the trigger to start the belt in short spurts and move the knob. eventually you'll get the belt to track on center.

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.