Berg Selectors and early A-Model motion cases were not equipped with chain tension adjusting hardware. The method for adjusting the chain was to move the hold down plate for the 45 tooth sprocket stationary pin. The sprocket needed to be rotated to four positions to loosen the hold down plate mounting screws behind the sprocket. The plate was repositioned and the screws tightened. The square notch near the center of the sprocket provided the access to the screws. The adjusting hardware assembly provides more accurate adjustment with less effort.