You have to embark on the spirit quest before Otto will waste his three wishes. You get some cosmic stamps.
Then, find Otto.
Note that now that you are this far McQueen is more willing to pick items up. You should visit places you have already tried to pick up things.
This is the low-spoiler guide for "Otto's three wishes" puzzle in The Darkside Detective. Unlike in normal walkthrough, you get gradual hints on how to solve the puzzle. Click the big button below to see your first hint. If the hint contains a spoiler, you will be warned about it before clicking.