Step 1 Examine your metal zipper to identify what may be causing it not to close. Look for thread or material caught in the teeth or a gap in the closure to identify the source of your zipper troubles.Step 2 Cut away any threads or fabric caught in the teeth of your zipper with a pair of embroidery scissors or a razor before attempting to pull the slide over the congested area.Step 3 Lubricate the teeth of your zipper by rubbing a bar of beeswax along them while the slider is pulled to one side.Step 4 Pull the slider from one end to the other a couple of times to fully coat the teeth.