Garage Door Openers

I have a two-car garage with automatic garage doors. When I moved in about 5 years ago, both doors worked. But on one side I could only close the door from the main switch and I had to hold it down to keep the door closing. This last weekend I cleaned out the garage and had to hose down a section that the mice had gotten into. Now the other door requires that I close it from the mains switch and that I hold the door down.

Both doors will open from the outside using the garage door opener. I can only guess that I've done something to the electronic safety "eye" at the bottom. But what? They look fine and I've wiped them off. There's nothing obstructing them from "seeing" eachother.

Anybody else had this problem?