Well, I searched a few more places here on these message boards. I found some remotes at SmartHome.com, then I looked at the requirements for X-10 control on those without the plug’n play button.

I had no idea that the X-10 transmitter also received the IR signal (they call it a Command Console, #4040.) The 15-1919T has a console that is the same, so I placed it correctly and now I have light dimming control again.

Thanks anyway, all!