Hi Les,
If your G11 is older I have seen them like that using the gear as a bushing. These aren't as smooth but for visual are fine. If imaging you will be better off with the later bearing ring gears. Be sure to use SuperLube, the food grade teflon version to keep the grease soft in the cold.?
The bearings allow better balance and reduce the load on the stepper and servo motors. I think they also have lower PE due to drag.?
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Chip Louie - Chief Daydreamer Imagination Hardware
Chip Louie