P-321 Main Spring for EDISON DIAMOND DISC Motor. The spring is NEW, identical in size to the original (1.5 inches wide with 3/4 inch center coil.) I have one of these springs left. This is always a very challenging and dangerous installation. At almost 79 years of age, I cannot install these springs any more. Please note: Springs are NOT returnable. Extreme caution must be used when working with mainsprings! NOT RESPONSIBLE for damages or accidents! Be sure of the direction the spring must be inside the spring barrel.