It's as if there's something between the two eye beam fixtures at the bottom of the door. Opens fine. But try to close and it reverses direction immediately. The only way to close it is by holding the button until the door is all the way down. The unit is from May '94, is 1/2 hp, model#(?) is HBW0777 or 41A4315-7A.

Thanks if anyone can help,

Lou

Lou -
I think you're on the right track. Try these steps to get it working again.

Clean the lens of the eye beam units on both sides of the door
Use a Q-Tip dipped in water or alcohol
Make sure the eye beam units are aligned
This doesn't have to be exact...just eyeball it or use a string to check the alignment.
Make sure the wires are attached on the back of the motor unit
And also that the wires on the back of the eye beam units are intact.

Surely one of these steps will do the trick.

Hope this helps.
WallyH

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Claudia, they are in the right place, see if the beam is working by interupting beam with your hand and not the Leds Change, If no change, it is a beam problem.
Can also be a force adjustment. May need Lube or look for something binding/obstructing.