After you get the gerbil out of the fireplace it will run on top of the grandfather clock.
Got the gerbil out of the fireplace
How do you get it on the move, again?
It sits on top of a clock, right? Those make quite a sound every... hour, I would say? ?
Move the clock time until it tolls.
And it is back in the fireplace! You get it out of there with the bog brush.
Yeah, it moves through the hole from room to room.
What would happen if you block the hole?
You will find something that will help you.
Open the top drawer in Lucy's room. You find some duct tape.
Use the tape on the hole when the gerbil is on top of the clock and make it move. It will run into the wellie. Pick up the wellie (boot).