I have a Craftsman Garage Door Opener. SOMEtimes the unit doesn't not close the door(when the green light is off). Other times the unit works like normal. In other words, this problem is intermittent.

Hi Rlong and welcome, check the wiring to the sensor and make sure it is lined up proper. Good luck

Hi. Thank you fro your VERY quick reply! I did make sure the sensors are lined up, AND I checked the wiring as best I could. Our door works 97 % of the time. It is usually, obviously, when one is in a hurry that the door will not go down. I'm wondering if it is a "Mother Board thing??" This is definitely Intermittent!!

Hi again Rlong, it's not likely the logic board. Describe what the door is doing when it fails, also post the model of your opener. Have you preformed a force test? Is the door balanced properly?

When the door won't go down, the sensor green light is completely out/blank/off. When the green light is lit, the door will go down like normal. I'm not sure what a "force test" is... I would have to say, the door could probably use a balancing. The Craftsman is Model #139.53975SRT1.

Hi again, page 21 of your manual will more than likely solve your problem, definitely read and follow that before buying a logic board. Also make sure the green light sensor is not in direct sunlight, that can cause your problem. Here's a link if you need the manual.

Craftsman Garage Door Opener Owner's Manual | ManualsOnline.com (http://homeappliance.manualsonline.com/manuals/mfg/craftsman/13953975srt.html?idRes=16793288)

Hello. I appreciate ALL your time!! I read my Manual. This door opener was installed professionally by Sears sub-contractor years ago. This unit/door has worked fine all these yrs. NOTHING has changed. This is QUITE annoying!! Again - because it occurs typically when one is in a hurry, & also - if it's broken, it should be BROKEN!! Not disable intermittently. Tx again for ALL your time! PS - When I find out WHAT is the solution, I will let you know.

Ok on the update, I would check closely the wiring going to the sensors, after years of use they can become loose or the insulation can be damaged, especially at the staples. Good luck

Green light off (on receiving sensor) means light beam is broken (means something is in the door way) or sensors are misaligned. Orange light off on transmitting sensor means no power to sensor.

If problem is intermittent means one or both sensors are not properly secured and are moving out of alignment because of vibration of door going up and down.

All as parttime said.

Light sensor can fail due to many reason. Usually the life span of a light sensor is very less. What you can do is try out some repair steps shown in the video www.YouTube.com/watch?v=qfuZOZ1hHTk‎ and if it doesn't work call your storage cabinet (http://www.garageliving.ca/garage-products/cabinetry/) provider so that he may be able to fix it.