Craftsman opener flashing 4 times
Purchased and installed Craftsman door opener October 2009, model 139.18458DM. Worked great until now. Door will open using remote but won't close. When trying to close door, begins to move then stops immediately. Light flashes 10 times. Door will close when pressing wall switch continuously. One door sensor LED is green and other is yellow. Checked sensor alignment. Cleaned lense on sensors. Vacation button is not activated...no flashing light on wall switch.
The LED light at LEARN button flashes 4 times then off for 4 seconds and repeats this cycle. During the 4 second Off Cycle, LED flashes 4 times so faintly it's difficult to notice it's occuring. If incandescent light bulb is on, the LED flashing during the Off Cycle cannot be seen.
Don't have an instruction manaul. Sure could use some help, thanks.