I’m posting this here as a public service for the future of humanity and the Net. Fixing a stuck Alpine in-dash three-disc CD player/changer: Take a thin but stiff piece of plastic (a very thin ruler will work, or you can try a piece of thin cardboard) and slide it in between the bottom of the disc cartridge and the slot into which it goes. Insert the plastic toward the right of the unit — when it hits the back wall, slide it to the left. You will hit a latch underneath the cartridge and the stuck cartridge will manually eject. Take out any discs in the cartridge, re-insert it, and try shifting between discs. Eject again, and repeat the latch trick as needed. Eventually everything will work right.