I have checked all serials and did not find RMA opened for “serial number old” reporting they are faulty. Contract is not transferable unless there is hardware failure on the product.
May I know the reason why you need to change serial number?
Please also note that, for rows highlighted in Yellow, the “serial number new” were already returned to Juniper, and no longer with customer. Their corresponding replacement serial number, are in fact already under contract# C1-3238492736. Can you verify with your end-user again the serials they are holding now?