The profile EbVT-EpsonHPn-carbon is from the 3880 zip file, and when I look, the two unused inks listed near the bottom are K and LLK. LK and LLK are listed as toner inks 1 and 2. Donʻt think I changed anything there, but if so, that might explain a few things.
Thanks for reminding me about agitating the carts before use. I had not done that, which could explain the uneven progression of tones. I agitated the carts and then got a nice tonal gradation from Keith Carterʻs profile B&W test image (www.northlight-images.co.uk/digital_black_white.html)