"...If the runner sees F1 throwing to 2nd and returns to 1st, it's a balk."
Dash Riprock, if the runner just has a big lead and F1 steps and throws to 2nd, then I've got a Balk. BUT if the runner runs half way to second, then upon seeing F1 stepping toward 2nd, he turns and runs back to 1st, I'm not going to call a balk. In my judgement, there was a possible play a second...
Do you think along these lines too?