I was looking at the field today, especially at the hanging tetras.
I'll tell you now, if you didn't figure it out already (and by looking at the topics thus far, it doesn't look like anyone has)...
- Putting a tetra on top will make it drop.
- Giving it any reasonable amount of force on the side will make it drop.
- A good whack to the goal about midways (like me hitting it with the palm of my hand with a bit of a grunt) will make it drop. (Note that you don't want to break the field, lest the thing that drops becomes your ranking.)
And one other thing about the tetras that may or may not be addressed soon...holding some of them, a loose nut in one piece of the pipe will cause that part to spin around. Know that if you're planning on building a one-pole grabber.