If the sound has gone out on your 16mm projector ... there's a good chance it's a blown Sound Lamp!    BRAND NEW  and  MADE IN THE USA  this  BAK  4 volt .75A   Sound Reproducer  lamp (also called an Exciter Lamp)  fits Bell & Howell 16mm Sound Projectors and other makes.  (Check your projector manual for the correct bulb type.)