LXI is/was the Sears house brand of electronics, and they never actually MADE anything. It was like how Kenmore apppliances are rebranded appliances manufactured by Whirlpool, Frigidaire, or whoever Sears could get to make them that year.

As for the LXI, I believe the big screens were manufactured by Pioneer for many years.

I would try the Pioneer codes, and maybe RCA or Mitsubishi if thhe Pioneer codes don't work, as these companies may have made various generations of the big screen models over the years.

You may find some identifying mark on the rear control panel that can narrow the search for the original manufacturer.