Replacement steps:

First, set up the pulley at the upper end of the sliding door.

open the top and insert the 6mm hexagon wrench into the round hole.

after loosening the screw, pull out the upper pulley in parallel.

then screw in new screws.

push the upper pulley into the gap between the screw cap and the inner wall of the door frame. In order to keep the upper pulley at a certain distance, a piece of cardboard is sandwiched between the upper edge of the door frame and the plane of the upper pulley.

then tighten the screws.

the upper pulley is installed. Remove the cardboard.

Turn the sliding door upside down, erect it, insert the screw through the round hole at the bottom, and hold down the lower pulley with your hand, so that the screw hole of the adjusting box can be perpendicular to the screw, and the screw can be easily screwed in. Tighten the screws with a 5mm hexagon wrench.

after screwing the screw into the adjustment box, turn it five times. At this point, the upper and lower pulleys on one side of the sliding door have been installed.