Garage Door Opener Constantly Cycling Up and Down
I have an old Chamberlain 1/2hp (1991) chain-drive garage door opener with pressure sensors. Last night the unit began cycling up and down by itself. It would not completely cycle to the up or down position, but would only travel about 1/4 to 1/2 of the distance, then cycle again. I waited until it cycled to the full-down position and disconnected the power. Anyone have information for the do-it-yourselfer to correct the problem. Thanks in advance for any assistance provided.