@Bryan Fran I thought it better, I played again and I found the way to win. The door is a bit uncomfortable to move, but it is a very nice level.
I gave up as the door was annoying (noisy and difficult to operate). By simply removing one red brick by the motor, the door would have moved nice and smoothly. If your intention was to make the level harder by making the door not work well, then I'll pass on your levels from here on in. Dropping the ball wasn't very intuitive and took many tries and relied on luck for the ball to go right. The rest was very easy but I got bored waiting for the lift to be right and just went for it and B got zapped.