DOD R-855 4 channel Mixer - probably works, or spare parts

Description

Part of a room of electronic equipment, stereo pieces, speakers, keyboards, and other wires and things. Time for a clean up to fit a
bed in that room!
This DOD R-855 Mixer has not been used professionally in a few years. I am not sure how to test it without setting up a system
that we have no space for. I am selling it as parts but think it works just fine.
We are cleaning out a room and need to get rid of extra stereo/musical equipment and there's a lot. I have not used this piece,
just plugged it in and it turns on and functions. It belonged to a relative who likes to play guitar and bought all this extra sound
processing and other equipment in depth. He was in a band at one point, so he may have taken it on a gig.
See pics - no returns.
No box or instructions. Free shipping in US.