9.3 The Buyer shall be entitled to avoid this Agreement, reduce the purchase price or request delivery of substitute goods because of a lack of conformity of the machine only after the Buyer has requested the Seller to rectify the defect within a reasonable period of time fixed by the Buyer and the Seller has failed to rectify the defect within such period or has refused to do so; this applies only if and to the extent to which the parties have not excluded the aforementioned rights.