Damon considered this carefully. "Your Doctor is an earlier version of the one in my timeline, Jamie. If I were to replace his time rotor now, the Time Lords wouldn't be able to call him back in the future, and very large explosion of antimatter might occur if I changed that. I can't risk it."

But still, he didn't want to disappoint Jamie, or the Doctor, and if there was even a chance that things would turn out alright if he changed the timeline...he sighed. "Not without asking the Doctor first. Not yours, but the alternate Fifth on the Plane, or the other one. He'll know if it's a risk worth taking."