Something has finally gone wrong on the Focus after nearly five years. A few days ago when the car was all iced up I tried to open the drivers window before it had apparently thawed out sufficiently. It grunted for a second and then the window freed up with a pop as the ice broke but it's now not a happy window motor. It goes down ok but on the way back up it stops half way and needs to be left for a few seconds before it'll close the rest of the way with a second press of the button. It's like the motor gets tired and needs a brief rest.
Is this definitely going to be the motor or is there any other possibility for the fault?