Nine times out of ten it’s the photo-eye sensors — a two-minute alignment. Here’s the full diagnostic ladder, simplest first.
A door that opens fine but refuses to close is the single most common garage door complaint — and the most commonly free to fix, because the close cycle is the only one guarded by the photo-eye safety beam. Any doubt about that beam, and the opener refuses or reverses, usually while flashing its lamp at you.
Run this ladder top to bottom; each step is more involved than the last, and most people never get past step two.
The photo eyes sit ~6 inches off the floor on each side:
If the beam is verified and the door still stops short of the floor or touches down and rebounds, the opener’s close-travel and force settings have drifted (or the floor gained a new mat). Adjustment dials/buttons live on the motor head and the manual shows the sequence — set conservatively: enough travel to seal, minimal force. If the door needs ever-increasing force to close, do not keep dialing it up; that’s the opener masking a binding door, and step 4 applies.
Watch the door close manually (opener disengaged). Sticking, scraping, or leaning points to tracks and hardware: a bent track section, failing rollers, loose brackets, or slack cables piling on one drum. These are the cases that earn a service visit — and they’re also the cases where continued button-pressing turns a small repair into an off-track cascade.
Most openers will close if you press and HOLD the wall button — constant-pressure mode bypasses the faulted beam. It’s useful to secure the house tonight; it is not a fix. Living in hold-to-close mode means living without the safety system, and it deserves a sensor repair visit this week, not this quarter.
That’s the sensor-fault bypass. Your photo eyes are blocked, misaligned, or wired-faulted; the opener permits closing only under constant pressure. Align/clean first; if the LEDs won’t hold solid, the sensor set or wiring needs service.
Close-travel limit set too long — the door presses into the floor, reads it as an obstruction, and reverses. A small travel adjustment fixes it. New weather seal or a new floor mat commonly triggers this.
Cold stiffens lubricant and contracts metal; marginal force settings and tired springs show up in winter first. A tune-up with proper lubricant and a balance/force recalibration usually cures the seasonal version.