Steve... Get a new one and you will have the same problem again, they are poorly designed in that all the flexing is at the attachment points. If you have ever caught a glimpse of them in your rear view mirror going down the road at 60 or 65, you will see they are under constant flexing. I removed both of mine and used some waterproof flashing membrane called "Fortiflash" on the back side. It comes in rolls that are 6 inches wide and is a peel and stick (very adhesive) . I cut several pieces to cover the entire backside including the holes. It give the fender some added stiffness and you will never have to worry about any further problems. Should be able to buy some at a builders supply or roofing company, maybe google it for more info., a construction guy building a new home down the street gave me some leftover (about 3/4 of a roll). I also used it to reseal the coroplast under the trailer where I had cut it open to do some inspection.
