I had that problem multiple times with 1.16. I thought it was because the Silverjet pinballs were magnatized and sticking not allowing to drain quick enough. I changed the balls to Pinball Lifes premium pinballs. (It states they are great for games with "magnets".) I have not had the problem since. Not sure if that was the fix or if it fixed itself. I do know the balls are less magnatized and are not sticking together like they had with the other premium pinball.