Hi Haucardiere,

to GameBoomers.
It's the lever that gives the grief. Here's the technique that helped me get past the jetpack:
Place your cursor to the left of, and just slightly below, the halfway mark on the lever control. Then click-hold, and drag your cursor up a little. The lever moves straight to halfway.
And make sure you're standing well away from the castle.
Try that, and see how you get on.

and keep us posted!