Good detective work there Felix.
Personnally I would say that if the marshals are likely to get their fingers on rotating machinery then it needs more in the way of guarding! When an eight year old marshal loses the end of a finger and the parents bring legal action I guess we will find out what was really meant.
Dadio, for his part, was only ever suggesting that he might run without a gear cover for bashing purposes but Chris Larner advised that his spur and pinion would suffer in a dusty environment.