It doesnt recognise cds - JVC MX-D401T Shelf System

There are a few possible causes. 1. Lens on laser pickups dirty. 2. The belt that closes the drawer also lifts the CD assembly to allow disc to spin. If the belt is loose, drawer may close but not be able to lift CD. Listen to mechanism after drawer closes. Do you hear the disc spinning up? or Do you hear a motor trying and then shutting off? You can also remove the case top and visually check these. 3. The spindle height may have slipped. 4. The focus and tracking may have changed with age. 5. The pickup may be bad. And finally the carriage may be stuck and not moving the Pickup(Laser Assembly) to its start position.