Repairing Window Muntins: Step 1
1. Holding the spreader vertically, place it square against the glass and one of the undamaged horizontal muntins. Draw a vertical line about 1 inch long on the spreader even with the muntin's outer edge. Set the points of a compass about 1 inch apart. Keep them aligned vertically as you run one point over the muntin profile. The other point traces the profile on the spreader. Cut along the layout lines with a coping saw or utility knife. Check that the final profile is smooth and matches the profile on the muntin exactly.