Just as a test I decided to experiment with race 13, the Munster National.
Here is the final results from the race.
There were 3 horses pulled-up in the race, Jims, Joshs and Dougs. Joshs horse was top weight and Jims and Dougs were weighted in the bottom third of the horses.
I re-ran the race and here are the results.
3 pull-ups again but this time it was Jamie, Darren and Martins. Darrens horse was near the top in weight, Jamie's horse was near the bottom in weight and Martins in the bottom third.
I re-ran the race again.
2 pull-ups this time. Two different horses from the bottom third of the weights.
So we have 3 versions of the race with eight different horses being pulled-up. I think these pull-ups are just random chance on which horse is having a bad day.
To test the idea about reducing pulled-up horses by 10lb, I took 10lb off every horse that pulled-up and this is the result.
A new horse, Stu's was pulled-up but two of the previous horses to pull-up, (Jim's and Darrens's) were also pulled-up even running 10lb lighter.
I am not quite sure what this proves. Maybe 8 horses from 17 runners being adjusted by 10lbs was too much?