For a cogent and clear explanation of cogging, which DD motors have it, and how to prevent it, please check this out:
https://www.celeramotion.com/applimotion/support/technical-papers/slotless-vs-slotted-motors/
Early '80s Technics SP-10s had the cogging problem which is why many preferred Denons. My vintage Sony PS-555ES has a brushless and slotless motor obviating the problem.