One of the biggest failures is Water Leaks in thru the top and does not escape out the bottom due to trash etc.. Clogging the drain holes in the bottom.
Thus next freeze, water expands and so do the doors once that happens they are trash.
Also over time they can begin to bend so much that a tight seal is not possible. Replacement is the probably the best option, one can temporary fix them but in our business if this freight gets wet your gona pay for more than just a new set of doors.
Inpect those doors, and if you have drain holes keep them clear. The earlier you see a bow or bend in those doors the cheaper its gona be to fix.