Deck Chg. Right Button Not Working

Hello everyone, I need help with my controller Denon DN-MC6000. The deck chg. right button not work and I don’t know why it not working. I have tried hard reset without none result. Can anyone help me with this? Thank you.

Most likely: microswitch under the button has failed, on the mc6000mk1 Denon used short lasting ones so it’s usually recommended to change them all once you go to replace some. Beware, mk1 is notoriously complicated to disassemble, repair centres charge approx 6 working hours for that.