Quinti responded overnight by providing additional ways to supply leverage to remove the part. In the meantime, Lee proposed that we use a special tool that adapts to the rivet gun to "encourage" the part to remove under additional pressure provide by the rivet gun. Worked like a charm!!!! Whew, what a relief. Sent email to Quinti to rush a new end cap and tool to me. In the meantime, updated the Garmin GPS with fresh NavData. Also fabricated 6 bushings for use with the seat belts and shoulder harness. Using the bushings, installed the seat belts and harnesses.