First, locate the adjustment screws along the bottom of the outside face of the door frame (shown) or on the door’s inside edge.
Turn each screw counterclockwise to raise the wheels—and lower the door—so that you can lift the door up and out of the track.
With the door set aside, vacuum up any debris and wipe the track clean. Spot a bend? Use pliers to straighten it.
Inspect the wheels and make sure they spin freely (cracked or flattened wheels need replacing). Spritz axles with lubricant. Fit the door back in place and almost close it, then adjust the screws to even up the gap between jamb and door, lifting the frame 1⁄8 inch above the track—and you’re ready to roll.