Upon request of the customer at the time the work order is taken, the motor vehicle repair dealer, mechanic, or apprentice shall return replaced parts to the customer at the time of the completion of the work excepting such parts as may be exempt because of size, weight, or other similar factors from this requirement by rule of the board and excepting such parts as the motor vehicle repair dealer, mechanic, or apprentice is required to return to the manufacturer or distributor under a warranty arrangement. If the parts must be returned to the manufacturer or distributor, the dealer, mechanic, or apprentice at the time the work order is taken shall offer to show, and upon acceptance of the offer, shall show the parts to the customer upon completion of the work, except that the dealer shall not be required to show a replaced part when no charge is being made for the replacement part.