The common case could be a tape head (probability up to 70%). Please check the DCC tracks during playing back prerecorded tape in the SERVICE MODE. In order to enter the service mode, switch off the unit, then press and hold both STOP and forward PLAY buttons and switch power on. Than insert a prerecorded tape and play it. Than using of counter button switch to ALL ERR RATE display. You see now on the display the state of every individual tape head channel. If the tape head and amplifier chip work correctly, all those positions show 0, the display looks like 00 00000000. If one or more positions shows F or another symbol other than 0, the corresponding channel is damaged.