Most decent-quality deadbolts should turn smoothly for many years. Whenever you buy deadbolts, do not just buy the cheapest one you can find. In addition to a longer life and easier operation, a good quality deadbolt is much more difficult for a thief to pick the lock.
The first step for this repair project is to determine the cause of the problem with your deadbolts. Open the door and try to operate the deadbolt with the key. If it operates smoothly, this tells you the problem is with the alignment hole in the door frame. If it still operates badly with the door opened, the deadbolt itself may be defective.
Most deadbolts come prelubricated from the factory with grease inside of them. If the deadbolt is difficult to operate but still extends with the door opened, it may just require some lubrication. Many dry or wet lock lubricants are available at most hardware and home center stores, or you may be able to find some lock grease at a locksmith shop.
If the deadbolt will not extend completely when the door is open, there is something seriously wrong inside of it. You can attempt to take it apart and try to find the problem, but your chances of repairing it are not good. It is best to buy a high-quality deadbolt to replace it.
If the deadbolt works fine with the door open, you must try to find the cause of the alignment problem that is making it stick. The tolerances between the deadbolt and the hole of the strike plate in the door frame are relatively tight. If something has moved or changed shape since it was installed, this can easily create the problem you are experiencing.
One common problem is the screws in the top hinge of the door have become loose. This allows the door to hang crooked in the frame, affecting where the deadbolt extends. Try tightening the screws in the hinges and give the deadbolt a try again.
If this cures the problem, remove the screws from the hinge again and replace them with longer ones that reach all the way through the frame into the 2x4 wall framing.
Over time, screws that extend only into the door frame can repeatedly become loose with increasing frequency.
The door itself may have become warped with seasonal changes in humidity and just normal wear and tear. If this happened and the door otherwise still seals and operates well, use a hand grinder and wood chisel to widen the opening in the strike plate and door frame. The moisture, which caused the warping, typically enters from unsealed top and bottom edges. Sand and seal these edges with paint or urethane.
