I tested the seal with a 3/4" strip of paper to see exactly where the seal was weak. Once I found the area (about 2" where the paper was not held fast) I removed the cowl vent cover and placed 3 strips of PVC electrical tape over the top of the gasket. I reinstalled the cowl vent cover and adjusted and retested with the paper and was pretty satisfied that it was now a good snug fit at the old low point. I then poured water over it and it held perfectly.
If at some point the tape fails, I will remove it and apply a thin layer of 100% silicone calk smoothed out to a uniform thickness in the "low" area and let it completely cure for several days before lowering the lid.
John
