Two chairs came to me with the top half of the upper back slats broken off. As is normally the case, the broken pieces were thrown away. I didn't want to disassemble the chairs because it usually causes more damage. Instead I routed a a straight and flat surface to ensure a good glue joint for the replacement piece. I then band sawed the back half of the curved slat from 1-3/4 stock, scrolled out the details, band sawed the final half to complete the curved slat, glued the new piece in place and sanded everything flush.