Rust around inner edge of cooktop frame

First, disconnected range.Removed two screws at each end under front edge of cooktop. Removed flourescent light, removed two screws holding aluminum back panel in place.Had assitant hold this panel up and out of the way. Removed two screws from each side at rear of cooktop. Lifted front of cooktop straight up allowing me to remove 4 aluminum cook top bracket supports held in place by one screw each. Removed frame and replaced in reverse order. This item should be stainless on black/stainless range so water would not cause rust where frame contacts cooktop.