If you are removing the inner liner of the door to replace the ballast, beware that the old liner is cracked around almost all screw holes and will be very difficult to re-install. This may be the best time to order a new gasket and liner.
I would also replace the hot wire that goes to the ballast that comes out the bottom of the door from the bottom. I made the mistake of not replacing it, re installed the door liner than when installing the new wiring the door light wire was brittle and needed to be replaced!