some how, some where the metal vent cover blew off my race car trailer. I went to my local RV parts store and purchased a cover. I went on top of my trailer to put it on, but I think that there are some pieces missing. The cover fits into the crank mechanism just fine, but what holds the hinge portion of the lid to the opening? It looks like there was some kind of sheet metal fasteners there at one time, but were probably torn off when the vent cover flew off in the wind. Do I now have to replace the whole vent opening? I have owned this trailer for 8 months and never opened the vent except when I first purchased the trailer.