What can be done when the track slips on my treadmill?

Usually if a belt slips off the pulleys, it's because of misalignment.
The belt is not tracking true, pulling to one side.

Step 1:

please see the video and diagram attached. God bless you

Step 2:

Step 3:

see the video and proceed according, use the common sense.

God bless you

I would try to tighten the rear roller a little and see if that helps.
1 start the treadmill and operate it at 1.5 mph then hild onto the handle bar and plant your foot against the belt at the front. If it slips tighten the roller 1/4 turn on each side. Then try the slip test again and repeat the process, do not tighten it too tight that will cause the belt to fold in teh center and be ruined. You May quite possible need a new belt. Take the belt lose and look at the underside and see if it;s glazed (shinny) or has pieces missing under the center of the belt, if so replace the belt and also clean the rollers front and rear, also flip the deck over it shoudl have a wax coating on the other side if that hasn;'t already been done.

Have you tried adjusting the rear roller bolts with an allen wrench? That usually works for me.

Unfortunately now I have a slipping problem that tightening the belt via the roller bolts doesn't fix. In fact, I feel as if the belt is too tight as it only lifts about 2" instead of the recommended 3-4". Hope we get some other ideas here!

There should be two bolts in the rear of the treadmill, one on each side. These bolts adjust the rear roller of the treadmill. The walking belt will always go to the side that is looser. To get the belt back on track, (if you can start the treadmill so the belt is running) tighten the bolt on the side that the belt has slipped to. Tighten the bolt a little bit at a time. If you tighten the bolt too much, then the belt will go to the other side. Also, depending on how the belt is frayed, you may need to replace the belt.

There should be an allen head bolt on each side at the rear of the treadmill going throughthe rear cover into the tail [rear] roller. Turn each one 1/4 turn at a time equally untill slipping is stopped. If belt tracks more to one side tighten slightly more on that side.

My belt is slipping I tighten both alan head screws to the max roughly 7 turns and still have the broblem

Several issues, drive belt that drives the walking belt could be loose but you should smell rubber if its slipping.
Something could be caught in the track causing extra drag, its easy to do if you have kids or pets
Check for when you last lubed the track and walking surface, with no silicone it will drag and bog at low speeds

There should be adjustment screws on the back left and right sides. The screws will be horizontal with the tread, and probably need an allen wrench to tighten. If the tread runs straight, tighten each side 1/4 turn at a time to keep them even. Check the tread after each adjustment, and stop as soon as the tread quits slipping.