§  1.337   Return of service.

   (a) If service of the subpena is made by a person other than a United
   States marshal or his deputy such person shall make affidavit thereof,
   stating the date, time, and manner of service.

   (b) In case of failure to make service, the reasons for the failure
   shall be stated on the original subpena by the person who attempted to
   make service.

   (c) The original subpena, bearing or accompanied by the required return
   affidavit or statement, shall be returned forthwith to the Secretary of
   the Commission or, if so directed on the subpena, to the official
   before whom the person named in the subpena is required to appear.