Presumably he's in a crowd of people? "milling bodies" means a group of people moving around in different directions. "like a pinball" means, erm, like a pinball (in the game of pinball, this is the little metal ball that you propel into the board and which then frantically bounces around).
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AngliholicWhat is "milling bodies?"People who are milling about -- that is, members of a crowd who are each moving more or less aimlessly as one thing or another in the environment attracts them. The human equivalent of Brownian motion.