I was given a garage door opener from 1994. Model number HBW0777. The case says Craftsman on the side, but I'm sure this unit is actually made by Chamberlain. It appears to be in decent condition, the plastic gears are not deformed at all. For now, the door is not connected to the opener. You will rightly want to point out that this thing is super old and not worth fixing. I'm a tinkerer and I don't like to throw things away if they are fixable. I am an opponent of the society of "everything is disposable" so if I can get this thing working, I want to try.
I do not have any remotes for this unit. When I press the hard-wired open/close button, the "bullet" travels a few inches towards the wall (the closing motion), then goes back to its home (open) position. The light does not blink. If I hold the button down, it goes a little farther, maybe 10 inches, then returns just like before. Again, no blinky light.
The sensors are connected and pointed at each other. For now, they are on a table sitting right next to each other. Their indicator lights are both on, and one of them goes out if I block their line of sight. I will run the wires to connect them properly later, if I can get this opener to work. If I point the sensors away from each other and press the button, it closes a few inches and goes back to open again just like before, but the light then blinks 10 times as expected when having a sensor problem.
The force knobs are right at their default halfway points, and the limit knobs appear to be at a reasonable position. I did try moving the "up" limit farther up, just to see what it would do, and it made no difference at all - the opener returned to the position it started at, which didn't go far enough to touch the limit contact. I put the limit knob back where it was.
Any ideas on things to check?