I recently revived my JVC XL-R5020BK CD recorder-player that had been unused for many years. If you're unfamiliar with this machine, it has three trays to play CDs and an entirely separate tray that both records and plays CDs. When I started using the machine again about a month ago, I found that the play-only trays would typically not read commercially produced CDs, which were the only ones I had to play on it. After using a Maxell laser-cleaning disk, the machine would mostly play the commercial CDs, but it was "struggling" to read them. When I began dubbing from commercial CDs to CD-Rs, the newly recorded disks played without any problem, even though they were recorded and played on different trays. Why do the newly recorded disks play without any problem, while the commercially recorded are still problematic? I suspect that somehow what seems enigmatic to me has an obvious tech answer—but I can't see it.