Got this unit without its remote. Have a few RCA universals. Is there a short list of codes that would allow the universal to work this player? Guidance sought.

There are 3 UEI setup codes which will control the NS-WBRDVD.  They are Video 2596, 3064, and 2675.  For remotes which need 5 digits setup codes , 22596, 23064, and 22675.
These code are usually seen only in newer remotes.

Here are some more options using older UEI remotes. Only one RCA remote will work, the RCRP05B.

[Link: community.insigniaproducts.com]

Since I wrote that post 7 years ago, newer remotes, as 3FG said, would have the proper codes already and would not require the complex programming detailed above. I recommend this one. It can fully control your player plus 11 other devices as well as do learning, macros, etc. It's also backlit

[Link: ebay.com]