Bifold wood and MDF (medium density fiberboard) bifold closet doors can be easily damaged if they go out of adjustment and are then forced to open or close. A wood door is, of course, solid wood while one made from MDF is hollow with a wood perimeter interior frame. When the doors are new, factory drilled holes in the upper and lower perimeter hold the pins and rollers that allow the door to function. After heavy use, or abuse, the holes get enlarged, the wood section splits, or the MDF skin separates from the wood frame. The single best way to repair the door and restore it to its original functionality is to repair the damaged holes.
Tech Team’s #935 which contains 6 dowel pins, each 1/2” x 2” is the answer. Simply drill out the damaged hole to ½”, glue the repair dowel into place and then drill a new hole for the door fitting and you are as good as new