Unit is actually an RDR GX255 but there wasn't an option for that.
The remote for this unit was destroyed and I've tried three different universal remotes, including a Sony, and all the Sony DVD codes they offered. Am currently trying with my Time Warner (Scientific Atlanta) AT8560.
For any code which elicits a response, all I get is "DVD 3" appearing briefly on the front panel display, no matter what button is pressed.
(FWIW, I checked on a replacement Sony remote. It seems for the past ten years the only price Sony knows for a remote, no matter how simple or complex, is $75; over twice what I've ever paid for any other remote. This is even more inane when I can purchase a factory refurbished GX255 complete for $85.)