I took the lower limit screw OUT.
It still rubbed, LOUDLY, in first and second on my small chain ring.
Okay, fine, I'll move the WHOLE assembly. I undid ... whatever the clamp is, I guess you call it a "boss" or something, I don't know ... twisted it just a few degrees, just barely get about 1-2mm clearance ... and locked it back down. No vertical movement.
Put that screw back in, screwed it in until I nudged the derailleur cage back just barely cleared off the chain. It spins with no noise now.
I had to adjust my cable tension to set the center chain ring up right. It's set up right now. Shifts perfectly. Every gear from absolute low to absolute high slides through that cage with no noise.
Fixed the upper limit, too. It just barely shifts (if I bring my upper limit in any tighter, I can't shift to high), and it's just barely cleared off the chain in the highest gear on the biggest chain ring.
I actually had to move the friggin' derailleur to get it to adjust properly.
By the way! This bike has about 320 miles on it. The center chain ring has very much variable teeth! Some have chips off the edge, some are half as long as others ... the lower and upper rings are worn some, too. I've managed to somehow tear this little low-end probably $10 crankset up! Oddly enough, the gears on the back look pretty much fine. Someone earlier supposed that my bike might have a busted tooth, which I thought was ridiculous ... nope, it's taking serious wear to the chain rings.
I want forged steel chain rings. I actually see how they come off now.
Sigh ... guess I should do the rear derailleur. next. It's only auto-shifted once, though.