The display might be a bad capacitor. I think E9 is the track for the laser jamming when flipping sides mine was not following the track right and it ended up needing a screw adjusted on the laser mech. to get it to follow the track. *Here is also a link to a list of pioneer error codes:
[IMPORTANT] List of Pioneer Error Codes Here is a link to the service manual:
https://manuals.lddb.com/LD_Players/Pioneer/CLD/CLD-D604/CLD-D604-EN_Service_Manual_Scan.pdf