Thanks Don, I should've mentioned the up force was at 9. I found and called the cust svc number 800-528-5236, and they made me lower the up force to 5, manually lift the door waist high and drop it. Since it slammed to the ground, their conclusion is that the door is not balanced and thus the GDO is doing all the work. they recommended a couple of repair guys to do what's called a Door Balancing. Does this make sense to you? Thanks again.

If it is stuck in the open position you will most likely find the trolley is jammed against the bolt just in front of the motor unit. You will need to loosen the chain enough to release the tension and then run the opener until the door closes. While the door is closed locate the 'up limit' on the side of the motor unit and turn this control 2 full turns in the opposite direction of the arrow printed on the cover. Tighten the chain.

I figured it out. Problem with adjusting the limit switches was due to a missing pin on a gear that is on the main motor shaft that turns another gear that moves a plastic screw that hits the up and down limit switches. In other words, the internal up/down limit switches were not getting consistant feedback of the garage door position. Nothing that a twisty tie from a garbage bag couldn't fix. So that problem was fixed. The garage door now moves and it now moves up and down without whacking the header going down and the stop limit bolt (protecting the GDO motor unit) on the way up. I knew I was wasting time when the manual says a single rotation on either screw would result in a 2 inch travel change. and nothing I did was consistant. It either hit the bolt or header or it would just HUM and not do anything. I think the original problem of why the belt's tention spring/bolt came undone was due to excessive vibration due to non-sufficient belt tension. As soon as i got the garage door operational, I noticed it was hecka jerky initially going up or initially going down. Mid-travel was smoother. By tightening the nut (collapsing the tension spring) to the 1.25 inches specified in the owners manual seemed to make the garage door much smoother. When I have the time, I'll adjust the force screws down. I think I have them maxxed out right now. I'll also test the safety/reversing feature. For now, it open and closes smoothly. I'm happy. So, while the owners manual didn't tell me to open the thing up, common sense told me to. Also, this unit has a diagnostic feature. When you press the LEARN button, it will light up the diagnostic light and blink. 5 blinks told me the motor was overheated or the RPM sensor wasn't happy. No mention of what the RPM sensor was. I'm assuming something was stuck. Anyways, adjusting the limit switches got it moving and once I cracked open the motor housing case and saw the limit switches in action and saw how misaligned they were, it was a pretty easy fix. Glad I disconnected the door so I could cycle the belt for testing without crashing the door. that made way too much noise at 10PM tonight. Once again, thanks for your help and I hope something in this helps someone.

Take off the cover and I'm sure you will find the drive gear is stripped. It is a white nylon gear just in front of the motor. You will most likely find some white sawdust also. This was part of your gear. The part number is 41A2817 and is available from Sears or your local door opener dealer. It should come with instructions.