Okay, just pulled the B20 brain out of the enclosure.
the brain can only slide out the back.
While pulling out the brain, the wires to the driver came unplugged from the PCB. There was not
sufficient length of wire to pull the unit out.
I then had to splice in an 8" length of speaker wire.
There is a small fuse located near the power transformer.
In summary, if you're gonna pull the brain, be prepared to lengthen the driver wires (white & black).
If you're not handy with soldering, Id recommend you let a tech do this.