Open the Storm Cellar and cross the Canyon
Place the compass on the marked fitting in Clockworks Court and enter the Storm Cellar. Catch the ghosts, then put the dropped stone on the floor panel to lift the gate. Pull the sheet near the bed and use Dark-Light on the gem painting. In Canyon Hall, vacuum the false wall to reach the Canyon. Cross using the hanging handles, releasing only over the next safe landing, then return to the far part of Canyon Hall. The Canyon Stairs side route holds a ruby on the right wall.
Take the Quarry gem before raising the sand
In the Roundhouse basement, investigate the sarcophagus and pull the hanging handle three times to expose the next door. Slide down to the Quarry. Move the minecart only twice before entering the recess it originally covered; vacuum the ruby from the web inside. The third pull blocks the sand drain and makes that recess inaccessible. After collecting the gem, finish moving the cart and clear the ghosts as the sand lifts you toward the upper exit. Restore the missing upper bridge with Dark-Light for the Boo.
Reach the Tomb and survive the mummies
Carry a web ball to a torch in the Antechamber, then burn the thick webs obstructing the passage. Keep going to the Tomb and open the sarcophagus. A ghost steals the clock hand before Luigi can take it, so this visit ends with a fight rather than a successful hand recovery. Flash each mummy to provoke its charge, let it collide with a wall, then vacuum away the loose wrapping and catch the Greenie inside. Clear all three to finish the mission.
Collectible checklist
Old Clockworks gems — #4 Storm Cellar, #5 Canyon Stairs, #6 Quarry
Boo checklist — Quarry: Raise the sand, then restore the upper bridge with Dark-Light. The Boo seen earlier in the sarcophagus cannot be caught there.