If the sliding doors on your shower or bathtub don’t glide smoothly, repair them soon. A door that drags on the lower track will eventually do permanent damage to both the door and the track. A dragging roller at the top of the door will wear and require replacement.
First, make sure the rollers on both doors are riding on the tracks inside the upper rail. Sometimes, one roller falls out of the track and the bottom edge of the door skids along the lower rail. In that case, you only have to lift the door and guide the roller back onto the track.
If an off-track roller isn’t the problem, you’ll have to remove the doors to adjust and possibly replace the rollers. Many doors have a small plastic guide at the middle of the lower rail. To remove this type of guide, just remove a single screw. Others have a guide rail screwed to the door (Photo 1).
With the guide removed, lift the doors out of their tracks (Photo 2). Then make sure the rollers turn easily. If not, apply a little silicone spray lubricant. Some lubricants can harm plastic, so check the label. If the lubricant doesn’t do the trick, replace the rollers. Most home centers and some hardware stores carry replacements. Take an old roller with you to find a match. In many cases, you can use a replacement that’s slightly larger or smaller than the original. But be sure the original and replacement edges match—either rounded or flat (see photo of roller types). If you can’t find rollers locally, type “shower door parts” into any online search engine to find a supplier.
Screw the new rollers into place and rehang the doors. You’ll probably have to remove the doors once or twice to adjust the rollers for smooth operation (Photo 3).