Check the sensors on each side of the garage door. They must be pointed at each other. They both have a small light that is lit when they are aligned correctly.

I also had a similar problem with my Sears Craftsman garage door opener. While Sears said the part may be covered by warranty, it would cost $65 for them to get it done. I am considering filing a class action lawsuit against Sears. If you would like more information on joining the class, please email a summary of your experience with Sears and/or the garage door opener, along with your contact information: name, tele. no., e-mail address. Thanks, Mitchell Rait. mrait@comcast.net

When you check the continuity on the receiving sensor (unplugged) it shows that it is a closed circuit. How can one check to see if is good or not? Light does not work on receiving sensor.

After reading your answers about checking the line up of sensors, I will do that again. Our model no is 139.53635SRT. Thanks