Thanks for the suggestion, Practical.
Prior to your reply, I was able to reach Mike at Dillon. He recommended the Flitz and said that in using it, I could not damage the die. That was good to know. He also suggested that I use the RT die as a sizer, as the resizing operation of the die also holds the case tight enough to keep it from moving during the trim operation. Hadn't thought of that, although it wasn't giving me a problem the way I had set it up.
Last night, I chucked a 9mm bronze brush in a VS drill, wrapped with one layer of patch and saturated with Flitz. It worked like a charm, and after four 15 second bursts on a low/medium speed, it completely removed the scratches and left a mirror finish inside the die. Haven't seen the inside of a die look like that, ever! I also reset the die to resize and will just lube any case that I run thru the trimmer.
Jim