ACR Electronics EM-2BA MEGAPHONE Product Support Manual page 9

11.1.7 Replace microphone and mouthpiece assembly (2). Align keyway,
and secure with the three setscrews (3).
11.1.8 Steps 11.1.1 through 11.1.7 complete the assembly of the
megaphone. After assembly, test unit in accordance with
Paragraph 6.0, Testing.
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Y1-03-0057 Rev. F