How do I toggle collision based on height?

I'm trying to make dripping coffee, but because the object is spawned on top of one another, they collide immediately and bounce off to random directions. the solution is of course to turn off collision, but I want them to pool and build up at the bottom, so I need to turn on collision. This bit of code was what I was hoping would accomplish that, but it doesn't work. the collision turns off, but never turns on again.

Any help would be much appreciated.

What are you saying the coffee moves up the screen and should begin colliding again and it doesn't work ? The event looks ok to me but I can't imagine the game.