I don't know if you saw this answer in your searching. It seems to help other people.
http://www.pcpuzzle.com/forum/viewtopic ... t=clearing
I remember it was one of the hardest things to figure out and it just took timing and timing and more timing. I must've done it 20 times and got the box to stop accidentally.
I just looked at it again, and here's what I did to get the box to stop on the middle of the conveyor.
Wthe conveyor is stopped, make the green arrows so that two point to the middle on one side and one points to the middle on the other side.
ie:
><<
>><
(Doesn't matter which, they'll switch back and forth as you go.) Then, push a box onto the conveyor at the top. You'll notice that when it hits the bottom, there is a split second when it's in the middle. It's all timing from there. As it hits the conveyor, hit the timer. If it stops on the edge, you're going too fast. Otherwise, it will stop in the middle.
The rest as I said, is practice hitting the timer button just right.
) - but what do i wrong??? have somebody another hint for me?