Claims for warranty are only accepted when they are made in writing, either by mail, facsimile, e-mail or other written document. Parts being subject of the claim must be held for DÜRR`s disposal, unless DÜRR decides otherwise. In case, the defect is proven not to be DÜRR`s fault, then Purchaser shall be liable for the cost that arose from DÜRR`s activities to remedy the defect, and the Purchaser shall pay such cost to DÜRR