If you never replaced the loading belt, it's probably long overdue @ this point. Also, based on your description and the error codes mentioned, it all sounds like the loading belt as the main issue.
Here are steps I took to replace the belt in my Mitsubishi, M-V7057 (704, 79, 99 clone).
Pop the tray out and unplug the playerRemove the clamper assemblyRemove the old belt, clean the pulley parts w/ alcohol, and then replace the belt (part VEB-1184 or maybe SCQ 4.0 belt size)Hope this helps.