Originally Posted by
1989Pre
...Why just the low sprocket? I looked closely at the chain and it seemed that when I got some chattering, it was when the chain looked like it wanted to jump off the side of the lower (guide) pulley...
This is only a hunch, not based on any real experience: When the chain is on the largest sprocket the pulley cage is going to be at it's most horizontal angle. It might be worth trying to add as many links to the chain as the difference in tooth count between largest and second-largest sprocket. This will lower the angle of the pulley cage and just maybe solve your problem.
Brent