Grinding narrows down fast once you can say where the sound comes from and when. Metal on metal up at the ceiling is usually the opener drive gear. A dry rasp that follows the door up the wall is rollers and bearings. A single crunch near the floor is debris in the track.
Listen from the right place
Stand inside with the door closed, press the button, and keep still. Sound carries through steel, so resting a fingertip on the vertical track while the door runs tells you more than standing out on the driveway.
Grinding at the motor head
A plastic drive gear chewing itself makes a dry churning noise while the door barely moves, or does not move at all. Chain units add a slapping note once the chain has gone slack. Screw drive units grind when the rail lubricant has dried into paste.
Grinding that travels with the door
Steel rollers with worn bearings scrape and squeal as they climb. Look at the roller wheels with the door open. One that has stopped turning and started sliding shows a shiny flat spot. Nylon rollers tend to go quiet for years and then get loud all at once when the bearing cage breaks up.
Grinding at the spring shaft
A dry end bearing or center bearing gives a slow, heavy rumble high on the wall, loudest in the first second of travel. That one earns attention, because the bearing is what keeps the shaft turning true under load.
The Santa Ana factor
Every autumn the offshore winds pack fine grit into open roller bearings and along the bottom of the tracks. Doors that ran quietly in August start rasping in October, and the cause is abrasive dust rather than a failed part. Wiping the tracks with a dry rag and vacuuming the bottom corners takes a lot of that noise out. Grit already worked into a bearing cannot be washed back out, so that roller is on borrowed time.
What the fixes run
A full roller set is an estimated $125 to $225. A bearing or a drum is an estimated $165 to $275. Opener repair, including a gear kit, runs an estimated $145 to $325, against an estimated $395 to $720 for a replacement installed. A tune-up that cleans, lubricates and retensions the whole system is an estimated $95 to $165. Guide numbers only.
Where the DIY line sits
Cleaning tracks, tightening the hinge screws between sections, and putting a light garage door lubricant on roller stems, hinges and the opener rail are all fine. Skip heavy grease on the tracks; rollers are meant to roll on a clean dry surface.
Anything carrying the door weight stays off the list. A torsion spring holds hundreds of pounds of stored energy, and the cables, drums and bottom brackets are the fittings that keep it there. A wrench on a winding cone without proper bars will spin and take fingers with it.
Note where the noise sits and whether it happens going up, going down, or both. Then have the balance checked before parts get thrown at it, because grinding that started right after spring or cable work is usually alignment rather than wear.