Quad 405, the output DC should be corrected by the opamp. Check whether the opamp gets the + and - power.
I see you have washers under the output transistors. Have you used insulating sleeves on the mounting screws? The screws need to make contact with the transistor case but not the heatsink. I was given a couple of assembled boards and whoever did the job used heatsink which the screws cut through and shorted to the heatsink. Sorting this got the boards working for me.
