Picked up a JE510 via eBay. Listed as "Powers On - don't have a disc to test with". Unit is very clean, original user manual still sealed in plastic, included remote. For $25 it was worth a shot. I grabbed a five-pack of Sony blank MD74s off Amazon to test with (still sealed).
When I powered it up and inserted a new, blank disc, it worked on reading the TOC for about 20 seconds, then put the word "Eject" on the display and spit the disc out. Repeated attempts were met with the same behavior