Door barely opens/ opens with physical lifting assistance

If you can't move the door manually with the lift disengaged, it is most likely the counterbalance spring has failed or slipped. Other problems would be stiction in the tracks or a stuck lock that should be disabled for a lift.

It sounds like your door is jammed. Look at the rail on each side of the door and make sure there isn't a latch that is preventing the door from moving.

Is the door stuck in the open position? If so the trolley is probably jammed against the bolt just in front of the motor unit. Loosen the chain enough to free the trolley and then run the opener until the door is closed. While the door is closed locate the 'up limit' on the side of the motor unit and turn this control 2 complete turns in the opposite direction of the arrow printed on the cover. Tighten the chain.

Make sure the door is running well with out the openers help first of all. If it is making this sound then look inside the unit with the unit unplugged for white shavings. If so you will need to replace the gears. Thanks BB

This is a common problem and I don't know of a fix.The limit switch assembly is available from Sears for $19.49.

It sounds like the opener is stopping because the weight of the door is tripping the lift sensor on the opener. There are two screws on the side of the opener to adjust the lift and close pressure. Find the lift pressure screw and ajust it higher to see if that remedies the problem.
Also, because you said the door will not stay open at the top when you open it manually, I think your springs are not adjusted correctly. They should hold the door open in the up position when not connected to the door opener. That may be the reason the opener lift pressure is kicking it out.
If you have to adjust the springs, be careful that you know what you are doing. There is a lot of potential for getting hurt if you don't know the proper proceedure.
Good luck.

YOU SHOULD PROBABLY GET A LIFTMASTER/CHAMBERLAIN UNIT THAT CONNECTS TO THE TORSION TUBE.

THESE WORK WELL IN YOUR SITUATION

Try this link
http://www.garagedooropeners.us/helpgifs/chamberlain_troubleshooting.html

Watch the door go up and down to figure out the problem, but it sounds like a problem with the springs. We have had similar problems with our garage and it is usually because one spring has more tension on it than the other so when it tries to go up one spring pulls more than the other and the door gets wedged on the rails. I have found this usually occurs when the springs get older and they usually break a short time later. The best solution I have is to check and possible replace the springs.

Okay...upon further inspection, my left spring has broken in two. Going to call around for some quotes to replace the spring. Thanks for the suggestions.