Step 5: Check for loose hardware, and tighten as needed. On swing-up doors, check the plates where the spring is mounted to be sure the screws are tight, and tighten any loose screws. On roll-up doors, check the hinges that hold the sections of the door together; tighten any loose screws, and replace any damaged hinges. Sagging at one side of the door can often be corrected by servicing the hinges. If a screw hole is enlarged, replace the screw with a longer one of the same diameter, and use a hollow fiber plug, dipped in carpenters' glue, with the new screw. If the wood is cracked at a hinge, remove the hinge and fill the cracks and the screw holes with wood filler. Let the filler dry and then replace the hinge. If possible, move the hinge onto solid wood.