If door locks become stuck due to corrosion, they will most likely be difficult to free. It is possible that several applications of penetrating oil or paraffin will be required. Door hinges, for example, can be lubricated with regular cycle oil. To release a stuck lock, use a spray lubricant such as WD-40; insert the tube firmly into the keyhole.
If a door rattles, lets in a draft, or does not close properly, the catch plate or striker can be adjusted. This is usually held in place in the door post by two or three screws. Loosen them just enough to allow the plate to move, then close the door; position the door as needed, then carefully reopen it. Tighten the screws and check the fit again.