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160 SOUND MOTION PICTURES
F. The Reproducer Does Not Track Properly This occurs when the needle jumps from the groove. See that the reproducer is not dragging on the record and that it is not hitting anything or otherwise being hindered from free movement. Put in a new needle. Try a new record. The swivel base on which the reproducer swings is mounted on a bracket, which in turn is clamped to the base by a bolt. See that the bracket is level and that the bolt has not loosened and allowed it to turn.
G. There Is Excessive or Insufficient Plate Current If this is noticed on testing the amplifiers replace with a spare the tube showing the condition. When two or more tubes on an amplifier all show low plate current at the same time try replacing the rectifier tubes on that amplifier. (The 41-A amplifier uses the rectifier tubes on the 42-A amplifier.) This may also be a sign of defective condensers. (See paragraph I, below, under the heading, "Volume Falls Off or Ceases.")
H. There Is No Sound from One Horn
1. A fuse may have blown out in the cut-out box, backstage.
2. If the fuse in the cut-out box has not blown out replace the receiver.
/. The Volume Falls Off or Ceases
1. If the system is a double one, with an emergency amplifier equipment, cut in the emergency amplifiers by means of a key on the system transfer panel. If this act clears the trouble, continue the use of emergency amplifiers until the service engineer repairs or replaces the defective regular amplifier, unless the trouble can be cleared in the following fashion:
2. One of the amplifier tubes may be burned out. If so, replace it with a new tube of the same type.
3. One horn may have a short circuit in the line or winding through which the sound current passes, thereby