How do I get up to the rainbow?

Hint 1 of 6:

You've probably learned by now that the lid on the left side of the screen
is very important here.

Hint 2 of 6:

And you've probably seen that the seesaw can be helpful in moving the
goblins to where they belong.

Hint 3 of 6:

But have you tried putting something on the lid without having a goblin
stand on it?

Hint 4 of 6:

You should put just a bowling ball on the lid.  Then see what happens when
you jump on the flagstone on the right (either goblin).

Hint 5 of 6:

The ball hits the seesaw.