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The safety sensors interrupt closing, which has the potential danger of crushing someone. They do not interrupt opening. Opening is interrupted by resistance that exceeds the settings of the up travel force adjustment. Over time parts wear and resistance increases. The manufacturers planned for this by adding a force adjustment feature. But before you use that, look for obvious causes: broken springs, worn springs, loose hinge hardware, tracks bent, tracks out of parallell, roller bearings missing, roller bearing grease solidified, debris in the track, and "birdnested" lift cables.
If after correcting these causes the opener still balks at the load, increase the force adjustment 1/4 turn at a time until the opener functions reliably. The force adjustments are on the body of the opener- labeled up force / down force, and have arrows indicating the direction to turn for increase.