The error means that the player is unable to read the table of contents (TOC) on discs any more.If it's an occasional error then you can try switching to TDK blanks as they seem to be easier for flaky players to read, but if it's happening regularly to all discs then your machine is unrepairable due to a total lack of spare parts.
On the plus side, there are millions of MD units now lying unused as folks have moved on from them and as they're mostly worthless people don't generally bother with trying to sell them. Almost every piece of MD gear I own has come free of charge via my local FreeCycle and Freegle groups. Whatever you do, don't buy a used player from anyone: they're all getting on now and the TOC error is an age-related fault which may occur at any time.
If you wish to see exactly what features other machines have then visit the superb equipment browser at minidisc.org
. The site is hosted but n longer maintained though so some information is out of date, but it's still the most comprehensive source of free information about MD available.
Sorry here's probably no hope for your MDS-JE480, but I hope that my reply has given you a practical alternative means of solving your problem.