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The older LiftMasters have a nasty habit of changing their travel limit adjustments a wee bit with each cycle. Eventually it becomes a problem with driving the door into the ground OR in your case driving the trolley up onto the bolt.
What you need to do is back off the uptravel limit adjustment. The up & down limit screws are on the opener body, with arrows above to indicate increase. Back off the uptravel limit screw 2 turns. The door should stop short of fully open. Slowly increse the up travel limit 1/4 turn at a time until the door is open enough to clear you vehicle.
Watch how far the door travels. Place a mark/piece of tape where it stops after correction. Watch how far it travels each time you cycle the door. If you see it creeping towards the bolt, back the limit screw off again. If you get sick of dealing with a old crappy Sears opener, don't spent one good penny on it. Get yourself a new Genie screwdrive for around $150 at homecenters like HomeCheepo. You get to keep the door, the tracks, & the springs. Just swap out the opener, rail, sensors, & wall console. You can do it in under 3 hours on a day off.
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