How strange that you should post this Isabel as I have just deleted the original game from my computer this very evening. Haven't had time to play it yet but it's high up on my to do list :-)
Can't really think of a clue for 4 expect perhaps again do something with your mouse that you might not think of doing immediately. Sort of the opposite of what it is telling you to do.
Arghhh got to 17 & am stuck, but have done 18,19,20 so just got to do 17 arghhhh can't get the propeller to keep spinning long enough & my hands hurt. going to tey again tomorrow