Thread: Needing to Eject and Reinsert Discs Multiple Times

Hi, I flashed my Hitachi drive (gdr-3120L v47) to iXtreme 1.51 about six months ago, but didn't use it for backups until yesterday. However, I discovered LT+ had been released for Hitachi drives, so before using it, I upgraded the firmware to LT+. I never tested 1.51 with backups.
I made 4 backups of my games. The ISOs were verified and properly SS and DMI patched with ABGX, and the layer breaks are correct. They were burned using ImgBurn, and the brand of discs are Memorex (No Verbatim at the store I was in) DVD+R DL. The Xbox itself is about 4 years old, making it one of the ones prone to overheating. It has redringed once and repaired (or replaced, not sure) by Microsoft if this makes any difference. My problem is when I insert a disc into the drive, the dashboard will say "Reading" and probably about 80% of the time the drive will thrash about, then reject the disc. By reject I mean the dashboard switches from "Reading" to simply "Open Tray". I'll eject the disc and reinsert, which either results in the same thing, or the drive accepts it. It seems to be totally random. Some of the discs are worse than others, it seems, taking as many as 8 reinserts, and some work on the first try. The retail discs of the same games work perfectly.
Is this problem due to the drive, perhaps the laser, or is this because of the Memorex discs? Could it be a flaw with LT+? Thank you for any help you can provide.