It is a sho with rear 6 CD player

If you can eject the cartridge, see if it comes out with only five cds. If it does, reinsert it with no cds, let it initialize, then eject it again. If memory power is lost while a cd is in the player mechanism, the changer can get confused when power is restored and will initialize and try to insert cd 1 to see if there is one in that slot. If 2 - 6 is already in there, it will jam up.