1. Check the speaker volume control setting (on the back). 

2. Check the resistance of the speaker with a voltmeter. (set the meter to resistance check, carefully touch the wires between the  terminals and the voice coil (the terminals are coated with a non-conductive material).

A good speaker will measure somewhere between 80 and 100 ohms.  (some of our units do have 8-ohm ones)

Readings that are significantly higher than this (1K ohm, 1Meg ohm or “OL”) are a pretty good indicator that the speaker is bad.  

Replacement speakers are available through Spare Parts Store on our website.