There seems to be a bit of confusion in regards on where to get the blue gear and green gear. To clarify, the blue gear is the first one you get,where you navigate through the room full of the page memos (three strikes and you're out!) in the bedroom. You need the blue gear to get further through the rest of the place. The green gear is a bonus one, located in the room with the hands that grab you through the wall and restrain you. It's in the same area where you get the yellow gear,but it's just past it (normally you can't get through without triggering the boss,so you'd have to find a way to get past it,which as i mentioned earlier,you can purposely get grabbed by one of the hands and let the boss run past you.)
Edit: To get the green gear,after you obtain the blue gear,go into the mist room. Enter the door that requires the blue gear to proceed. Take the first door you see after,and go left and enter the other door,where you see a long hall way. Near the end of this hallway, is a chest,containing the yellow gear. If you keep proceeding right after this chest with the yellow gear,you'll run into the boss,where you'd have to run left to escape it. To get past the boss,get grabbed by the hands and let the boss run past you,then head to the right,into the door,where you'll find another chest containing the green gear.
Head back into the pink mist room and you'll find a hidden door tucked away behind the three crates in the bottom right of the room. Upon activating it, you'll hear a chest drop, and if you head back to the place where you saw the giant clown,where you got the golden KEY, you'll get paradise key IV.