Just looking at the equipment, you shouldn't really have a gap there so I agree, maybe a different drill on the Fast might help.
I would think there shouldn't be a big gap between the Furious 2000+polish and the Fast, they should be both compliments. It's hard to envision another ball in there. Maybe if you try extender polish or a little heavier polish on the 2nd Furious, you might close up the gap.
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