Look back rule - ASA 8-7-T

[teebob21]

I need a refresher on a specific situation with the look-back rule. What are the obligations of runners after the BR has reached first base and continues to run? A strict reading of the rule makes me think that once the ball is in the circle and the BR has reached or passed 1B, all runners are under the LB rule.

Situation: R3 on 3B. BR walks on ball 4, reaches 1B and continues nonstop to second. The ball is in the circle, no play on either runner made by F1. R3 advances 8-10 feet towards HP as BR continues toward 2B. R3 starts "dancing", hopping forward and back several times in an attempt to draw a throw. Out or no?

As plate umpire, I called a Dead Ball when I saw this. I immediately thought I had goofed: this was a 3-umpire game and that runner should have been the responsibility of my U3....PLUS I brainlocked on the rule (thus this post). We hand-waved away the dead ball and life went on with runners at 2B and 3B. My partners think we got it right on the field. I think I should have called the out and returned the BR to 1B, even if that means stepping on my partner's primary call. (Which I apologized for in postgame...)