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.

Hint 6 of 6:

So position one goblin on the low end of the seesaw the next time you use
the flagstone and bowling ball.  The goblin on the seesaw will be sent up to
the top of the screen with the rainbow.