A lesson I would like to share: don't adjust the trunk eddy sensor too sensitively. I did so, but what tended to happen is that the sensors would start to self-trigger when the machine warmed up. Should this happen while you have two balls locked and are ready for multi-ball, this can make the machine go a little haywire.
Long story short - I learned that triggering the trunk magnet and the sub ball release simultaneously can exceed the capacity of the shared circuit, blowing the fuse. I'm glad the fuse did its job, but I don't plan on doing anything that blows a fuse too often.
I managed to do this twice before I backed off the adjustment of the trunk eddy sensor a bit more from the edge.