Jack easily did as he was told and snapped the casing back over the valve when he was finished replacing it. He had to admit that it started to sound better already. More of a regular radioactive hum than the evil, nasty sound he'd heard when he first came in. Without wanting to spend too much time in the room, Jack hurried to the door, knocking on it quickly. "All right, we're done! Can you please let me out? I don't want my hair to start falling out!"

Also, he wanted to get back to John to make certain he wasn't cannibalising the TARDIS for valuables or anything.