Fix sagging shower doors by tightening the pivot screws. In most cases, the screws cannot be tightened because of stripped or worn-out screw threads. If this is the case, replace the worn-out screws with new ones or bigger ones.
Before you begin the repair, gather a screwdriver, substitution rollers, a two-by-four block, shims and a mallet. Begin by removing the door from its track by slackening one screw at a time on the door. Place the two-by-four block under the external bottom corner of the door. Slide shims between the two-by-four block and the door. Place a piece of wood against the base corner of the door. Tap the underside of the square of wood slightly with a hammer. If possible, have someone hold the door steady for additional stability. Drive the shims in tight once the door is higher. This keeps the shower door from hanging down. Proceed in this way until you achieve the required height. Tighten all the screws, and close the door.