I am going to attempt to visualize this for you, if at all unsure do not try this till we confirm what we are trying to do----
Something just is not right if you are getting audio with no bias esp if the right channel is clean so ---
Look at the amplifier blocks and the 4 white block resistors on each one. We want to see what kind of millivolts the outputs are actually seeing. With mini grabber hooks on the end of your meter and the meter set to dc mv scale clip one lead to lets say top left leg left side white emitter resistor and the other lead to top right leg right side emitter resistor of the same block. What we are looking for is a mv reading. Need to do this with the unit on the dbt and hook up the leads before you turn it on. If you get a reading note what it is and report back, and please please ask first if not sure what we are trying to do here.Once you get a reading we can convert that to ma values.