How do I get the guitarist's note?

Hint 1 of 7:

Well, once you get near him, it's really not all that hard.

Hint 2 of 7:

Some items on this screen work differently when a lot of weight is placed
on them.

Hint 3 of 7:

Like the weight of two different goblins.

Hint 4 of 7:

You'll need to use the spring that made the pump appear.