my mother in law has a hinge problem with her bi-fold closet door that recieves alot of use. I repaired the problem 3 months ago, the upper hinge was really the culprit, with 1 screw completely out and the other ones just loose. I also used tooth picks in the upper hinge and carefully tighten the other hinge screws. the repair lasted 3 months, and now has the same problem.
the door is a hollow core with 1/8th in. laminates which the screws go in. every thing seems to line up nicely. What can I do to make the repair more lasting? there is a limit to going to bigger screws. thanks snuffs

 

There's a solid frame around each section of the hollow core doors that should be at least 3/4" wide. You can replace the seperate hinges (probably 3 of them) with a continuous piano hinge. Use one narrow enough so that the screws are in the solid part of the frame.