How do I fix the pisto-laser?

Hint 1 of 8:

The dissidents who gave it to you said you needed a crystal for it.

Hint 2 of 8:

There's one on Celebration Island.

Hint 3 of 8:

As you're facing the Dark Monk's temple, go left, and jump over the lava
flows.  You may need to land on the blocks floating in the lava.

Hint 4 of 8:

Then climb the ladder, and you should be within reach of the crystals.