Hi,

I've got a Sears 1/2 HP garage door opener (model 139.53535SRT)that
I've installed back in March 1996. The double car wooden garage door
by itself (i.e. without garage door opener)works. Also, the garage
door opener when opening the garage door works. The problem is that
the trolley itself (without the garage door attached) goes down only
goes a few inches, then backs up and the white lights flash. There
are no obstacles in the way at the base of the garage door. The
little green light on the side panel also blinks 4 times although I
can't find what that means in neither the manual nor the inside cover.
I've lubricated the tracks for the garage door, the hinges, as well
as the chain. I also greased the T-rail as well as the gears (which
look fine) inside the unit and it still won't close. I've tried
increasing the down force to where it is nearly at maximum setting.
I've also checked the safety reversing sensor and both sides have
their green lights on to indicate that a connection from the beam is
good. Can anyone help with what the problem may be? Thanks in
advance.
Jay