The only ruck ones that seem obvious to me are the blocking ones when 1 ruck jumps into the other ruck and the ball drops over his shoulder without him touching it. Thats about as clear as you get with stopping the other ruck from competing.I don’t know so much about the last one. To me it wasn’t a free but I reckon 90% of what is paid in the ruck are not frees, nothing to do with game sense.
I'm as confused as everyone else on the other ruck frees that are paid, but those ones where they jump in and then don't touch the ball seem pretty obvious to me.