Boy are you correct. Been there done that.As for the speakers and different voices. When a unit is new all speakers are set for a set decibel range ( all the same) speakers should remain in the same group. Mixing speakers from different sets will at times have delayed or no target. Yelling at speakers wont do any good. Replace the speaker and when repaired set range for that speaker group. Setting range is done by replacing resistor which is soldered between the speaker wires.