There have been a couple people that reported adding a small extension to the antenna helped this problem. The antenna is that small grey wire hanging down.

I had a similar problem and posted on another question just a few minutes ago. I found that the receive antenna is set at the factory by chimpanzees... and they don't spend any time getting it in the middle of the range... just set it to work on the bench.

My brother pulled the circuit card and analyzed the wiring. He found the receive antenna section and took some measurements. He told me that the cold weather that had set in had shifted the effective frequency of my receive unit.
There was a potentiometer with a small screwdriver slot that he used to set the response to my sending unit... so as I backed away from the door, the made adjustments on the unit.
These problems all sound just like mine... and I am beginning to wonder if Sears sets them on the ragged edge on purpose to make the extra service call money after their warranty expires.

If you can find someone who designs or workw with circuit design, you can probably get it adjusted for the price of a beer!

Ah another great conspiracy uncovered. And electronic technicians will work for the price of a bottle of beer. I feel over paid handing out free advise.