Hi there. A few years ago I tried emailing Fryette Support looking to purchase a new input panel assembly for my FB412 because mine had failed. I was not able to get a response at that time. It looks like with this forum now actively monitored again, it may be worth another shot.
I have wired it to mono in the meantime but want to wire it back to the stock setup so that I can play around with stereo sounds. Since the replacement part request form requires a forum post, here it is.