If your door is grinding, jerking, or hanging unevenly on one side, that's almost always a spring or cable issue, not the opener - the opener just doesn't have the strength to lift a door that's lost its spring tension, so it strains instead. A door that reverses right after the floor is usually a photo-eye out of alignment, common after a car bumper or a broom clips one of the sensors. Slow response to the remote but fine on the wall button points to a dying remote battery or a receiver issue, not a mechanical fault. And a door that's fine most of the year but sticks hard on the coldest mornings is doing exactly what aging grease and a stiff torsion spring do in a severe winter climate - it's not broken yet, but it's telling you the lubrication schedule is overdue.