Ernest the Chicken

Enter the manor.

On the first floor, grab the fish food in the room south of the staircase.

On the ground floor, take the poison from the room south of the kitchen, in the northwest of the manor.

Use the poison on the fish food.

Exit the manor through the eastern-most room (or teleport to the Draynor lodestone) and walk to the fountain in the southwest corner of the yard.

Use the poisoned fish food on the fountain.

Search the fountain for the pressure gauge.

Walk along the west side of the manor until a compost heap is found.

Search it for a grimy key.

Go inside the manor and enter the small room behind the staircase.

Take the rubber tube.

Return to the entrance hall of the manor and go into the room to the west.

Search the candle sconce on the western wall to open the wall.

Climb down the trap door ladder to the north in the new room.

There will be a puzzle with the solution as follows.

All levers start in the "down" position.

Pull levers A, B up

Enter Door 1

Pull lever D up

Enter Door 1

Pull levers A, B down

Enter Doors 3, 4 & 5

Pull levers E, F up

Enter Doors 6 & 7

Pull lever C up

Enter Doors 7 & 6

Pull lever E down

Enter Doors 6, 8 & 3

Go through Door 9 and obtain the oil can.

Leave the basement.

Pull the lever on the eastern wall.

Go up the stairs, then up the ladder, and talk to Professor Oddenstein in the room to the east.

Talk to him again.

Quest complete!