The Service Elevator (Service Lift in the British English version) is a room inside of the Old Clockworks in Luigi's Mansion: Dark Moon. This small room has two floors that are only explored during one mission. The Service Elevator, as the name implies, has an elevator, although it is nonfunctional. A stack of gears blocks the door to the Cargo Room and a safe is inside of the elevator. There is also a Pixelator on the first floor. The basement floor only features a walkway with a pit of sand below, and no way to access the elevator. On the first floor, the door on the left would lead to the Cargo Room while the door on the right leads to the Gear Chamber. On Floor B1, the door to the left takes Luigi to the Maintenance Hub while the door on the right leads to Floor B1 of the Gear Chamber.
During Piece at Last, Luigi is automatically pixelated into the Service Elevator room. Luigi can shine his Strobulb on the safe to make it drop down slightly. After freeing Toad, Luigi must make his way back to the Service Elevator in order to use the Pixelator to send the assistant back to Professor E. Gadd. If Luigi activated the safe before rescuing Toad, while he is walking back, the safe crashes into the ground and release many bills. Once the Toad is brought back to the Pixelator, the mission ends.
Only during Piece At Last, Luigi can pull off the cloth on the mirror to reveal a ruby on the other side of the railing. In order to get this ruby, Luigi must bring the Yellow Toad to the Service Elevator room. Before using the Service Elevator, Luigi can pick up the Toad and launch him onto the other side of the railing. The Toad automatically collects the gem and any treasure on the other side and then hands them to Luigi when he returns. Back in A Timely Entrance, Luigi would've been able to peek through a pipe into the Service Elevator from the Cargo Room; doing so would've shown him the Toad attempting to reach the gem on his own only to fall down into the B1 floor as two watching Boos follow.
In the bonus mission Outlandish Interruption, Luigi can return to this room from the Cargo Room as the gears that originally blocked the way will no longer be there; there is nothing of interest nor do any ghosts appear in this room or any of the other rooms visited in Piece at Last, however.