The Clockmaker's Chambers are accessible in missions C-3: Roundhouse Brawl and C-4: Play Catch. Luigi enters the room from the Warehouse after taking a lift to the upper section.In mission C-3, one corner of the room is a bed with a sleeping Greenie who has a bucket on its head and a Gem under its arm. The rug in the center of the room can be vacuumed up revealing a rotor mechanism. When Luigi uses his Poltergust 5000 on the rotor, the digital clock next to the bed with change. If Luigi sets it to the correct time (9:00), the alarm will go off, waking the Ghost and allowing Luigi to capture it. Once the Ghost is caught, it will give you the mansion's seventh Gem. The Gem can only be found in mission C-3. That is the only Ghost that appears in the room with an exception of the Polterpup briefly hiding in the room.