The leftmost knob is broken. The stereo out knob, the B output is inoperable, but A can be turned by holding the base. Effects are applied, and there was no crackling or noise. When turned on, the switch doesn't turn off, so this is a junk item. How about it for someone who can repair it themselves? The box is as good as new. No instruction manual. I am also selling vintage effects units as part of a gear clear-out.