Step one: Pull the door release and operate the door manually...see if it is binding up...if it is easy to operate without the opener, then you have an operator problem. With the door released, cycle the opener up and down and watch the trolley on the track and see if it is smothly moving the full distance. Btween these steps, you will find the culprit....spring tension changes on the door would make it harder to lift, no go down, and do not adjust them,...torsion springs are not a DIY adjustment...if the operator (opener) jerks or the trolley catches and isn't smooth, then you have a sensor problem or the screw needs lubricated, etc.....check all of these and see what you find. Overhead doors do like maintenance from time to time...lube the rollers, make sure the tracks are secure (not allowing a catch point for the rollers, etc.)
There's some great broad stroke suggestions in this tip. I have an old Master Mechanic chain-drive opener. I followed these steps and found that even with the garage door released the trolley would stop and return. It didn't look to be binding up though. I decided to do what my dad always did when mechanical things conjured up mysterious problems - I hit it with a few shots of WD-40 the length of the chain. Ran smooth as butter. Now, I know that WD-40 isn't a lubricant and all the reasons not to use it on chains, gears, bearings, and stuff but I can't help but wonder what magic lives inside a that wonderful can that has brought smiles to generations of DIYers.