I need to replace the white plastic trim strip (part #12-46-11) in the center of the rear bumper on my 1964 Amphicar. I can't figure out how to remove it. It seems that the polished metal molding strip needs to be removed and the strip slid out of the channel. But the metal molding is attached with screws whose heads are beneath the plastic trim strip. Is the only option to cut out the old, hard strip on the car, then perhaps the new supple strip will press in to place? Thanks for any advice.