The feed dogs on each machine determine which feet work best on a machine. The original feet for any machine were designed to work well with the feed dogs on that machine, but other feet can work well too. Place your snap-on Pfaff feet on top of the 66-16 feed dogs and see how they line up with each other. If the feed dog teeth have a solid surface of the foot directly over them, the foot will probably work ok on that machine. If the foot surface is wider or more narrow than the feed dog teeth, your fabric may not feed well.
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