The tracking number you have won't work until the item is scanned as delivered, if it shows nothing in the system, then it hasn't been delivered. If it is not insured, then the buyer can file the Paypal dispute and you will be out the money and the part. USPS won't pay if it is not insured. If it is insured, my local postmaster will not file a claim until 30 days from ship date. This has happened twice. Not sure if they all do it that way...