NFA branch needs to read their own handbook.
https://www.atf.gov/firearms/docs/undefined/atf-national-firearms-act-handbook-chapter-10/download
10.1.5.1 Reactivation of DEWATS. Deactivated War Trophy (DEWAT) firearms may be
returned to a serviceable condition. A DEWAT that has been returned to a serviceable condition
(or reactivated) is often referred to as Reactivated War Trophy (REWAT). The act of returning a
DEWAT to a serviceable condition is considered the “making” or “manufacturing” of a firearm
by ATF. The procedures for reactivation by a non-FFL or FFL with other than a manufacturer’s
SOT status or with no SOT status on Form 1 are found in section 6.6 of the handbook. The
procedures for reactivation by an FFL with SOT status as a manufacturer are found in section
7.3.3 of the handbook.
https://www.atf.gov/firearms/docs/undefined/atf-national-firearms-act-handbook-chapter-6/download
Section 6.6 Reactivation of a registered unserviceable NFA firearm. The Form 1 may be used to
reactivate a properly registered unserviceable firearm, including registered unserviceable machineguns.
Block 4(i) of the form should indicate that a registered unserviceable weapon is being reactivated. The
remainder of the form should be prepared and submitted with the making tax in the same manner as
described above except that a law enforcement certification is not required. The existing serial number
on the unserviceable firearm should be used. If the reactivation will be performed by a Class 2
manufacturer, see Chapter 7 for additional information.