Assuming there is not any wear to the shaft or the hole, it shouldn't be glued.
The silver cup that's mounted in your roll arm has a magnetic ring (visual in your pic.).
If you press the parts together, the shaft fits snugly into the hole in the center of the cup, and the magnet holds the cup over the roll motor armature very strong.
Caution though.
There is a correct position for the roll motor before assembly, so that the camera is level, so research that too!
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