How do I implement this elevator?

I'm trying to create an elevator for a physics based 'ball-roll' game (the idea being the ball rolls by itself with the player only interacting with the obstacles). The problem I'm having is efficiently and effectively implementing an 'elevator'. The one I've made so far uses a physics impulse to move the platform itself upwards, like all other obstacles in the game.

The problems I'm having are:

1) A script has been set to apply 0.03 impulse to the ball when it collides with the elevator, but this seems to randomly happen. The same happens with the blue 'movePltfrm'.

2) I can't find an efficient way of stopping the elevator when it hits a marker but not collide with the ball.

I'm still fairly new to the engine, so I'm eager to learn what would be the most efficient ways of implementing an elevator like this, as well as any other input on the game so far as a whole. All help is greatly appreciated!

megafileupload [DOT] com /17uw/elevateTest.capx

I'm not sure what you are trying with the collision-impulse, but adding a condition elevator compare Y > 250 to the yellow button pushed event seems to work for question 2..

I'm not sure what you are trying with the collision-impulse, but adding a condition elevator compare Y > 250 to the yellow button pushed event seems to work for question 2..

Thanks. The input technically works, but the elevator loses function instead of stops dead. What would you suggest to stop the elevator at the peak? I can't think of a way to make it stop completely.

you could set the elevator immovable..