Hi Mark,
The serial #'s are BF on both machines - March 1966. I haven't looked "under the hood", but I suspect it's the the timer with the advance motor on one end with the long metal bar that extends into the timer. I remember an old post with a picture of one of these timers a long time ago, but I've never seen one myself. I just remember a complicated looking gadget with wires going everywhere. That's all I'm going to say on the subject. I'll leave the rest up to Drew to post during his restoration. Thanks for asking.
Michael - I didn't ask the lady much about the history of the machines. I mostly wanted to get them loaded and get back on the road.
Brian