On Oct 3, 10:35*am, fcnorton wrote:

In addition, the as the certificate holder the previous owner was
required to fill out the reverse side of the current airworthiness
certificate and return it to the FAA. *


Wrong.
Seller sends the FAA the old REGISTRATION Certificate, not the
Airworthiness Certificate!
Buyer submits an application for new registration with a bill of sale
(and fee) to the FAA.
Do not remove the Airworthiness Certificate from the aircraft!
Please consult with your FAA FSDO or see faa.gov for the correct
process.