The rumble lid is a compromise fit at best. Look at the other 3 corners and see if there is a large gap that would allow adjustment to fix your contact area. If so, the adjustment is in the pivot bolt of the hinge. It is a very coarse adjustment, so it may be difficult to get it exactly where you want it. If the car came with the rumble, there should be a wedge spacer at each top corner of the opening, to center the lid when it closes.