DEAR TIM: Several door locks at my home don't work properly. When I try to extend the deadbolt lock, it will not turn all of the way. Several other regular door locks and deadbolts in my home are hard to turn. All of these deadbolt door locks used to work perfectly years ago. Are they just worn out and I need new door locks, or is it some other issue? Greg B., Carnegie, PA

DEAR GREG: Your deadbolt dilemma is fairly common. There are many reasons why door locks begin to stick and become problematic. Some can be traced to poor workmanship when they were installed, and Mother Nature can place a hex on these pieces of hardware if she gets cranky.

If you have ever had the pleasure to install a regular door lock, a deadbolt or a simple door handle, you will discover that the latch or bolt mechanism moves in and out with a fairly close tolerance. In other words it doesn't wobble much as it moves. Add to this the small opening in the metal keeper plate that is attached to the door jamb and you can see that it is mission critical that the keeper and the latch mate almost perfectly.

The latch of the deadbolt lock needs to line up squarely with the metal keeper plate in the door jamb. PHOTO CREDIT: Tim Carter

Since you say the locks used to work well, I will assume that they were installed correctly. You need to start an autopsy to see what is the cause of the problems. The first thing I would look at is to determine if the door is warped or if it does not hang square in the frame. Either of these two or a combination of the two will cause a door lock to malfunction.

To see if the lock latch has dropped or raised in relation to the keeper plate in the jamb, I usually extend the latch and slowly allow the door to close so the latch is in contact with the outer edge of the metal keeper plate. Use a pencil to mark on the edge of the keeper plate the top and bottom points of the latch. Open the door and see if these line up with the top and bottom openings of the keeper. If not, you can move the keeper plate or use a rotary-grinding tool to enlarge the keeper. These tools work well and often solve the problem in a minute or less.

But before you turn on the grinder, you can check one or two other things quickly. See if the screws in the door hinges are completely tight. The top hinge is the most important one as the force of gravity pulls at this hinge constantly. Frequently you will discover the hinge screws are not tight by just a half turn. Just tightening the screws may solve the problem.

While you are checking the hinge screws, tighten all of the screws that connect the door locks and deadbolts to the door. Do the same with the keeper plate in the door jamb. Remember, the tolerances in the door locks are tight and if one or more things are loose, all of them combined can lead to the door locks not working.

The issue may be seasonal swelling. This is a very common problem in parts of the country where the summer heat and humidity cause wood doors to swell. Perhaps the top and bottom of your doors were never sealed. You can check the bottom with a mirror, and stand on a ladder to see the top of the door. Wood doors must be sealed to ensure they do not warp or swell.

Door locks and deadbolts can wear out, but only after heavy use for many years. It is possible for an inexpensive lock to fail in a few years. I have door locks in my own home that operate smoothly after 22 years of heavy use. It pays to purchase quality door locks in the beginning.

Sticking locks may just need to be lubricated. Spray lubricants often do a superb job. But keep in mind that the locks are often shipped from the factory with a thick-bodied grease. You can get small amounts of this from a traditional locksmith or a traditional hardware store. You may get lucky at a home center and find some in the sea of products.

Always check the deadbolt action with the door open. The same goes for traditional door locks. If the locks operate with ease, and the latches and bolts fully extend, that tells you the problem is with the alignment of the keeper plate in the door jamb. It could also be that not enough wood was excavated in the door jamb. All of these things need to be checked closely.

I received this helpful tip from Jeremy Wrenn.

"Good article. In regard to the screws in the top hinge, we often find that the screws that are supplied with the hinge are typically short and only penetrate into the frame. If the door is particularly heavy, the screws often times strip out the wood in the frame and won't hold. We find that getting a screw into the 2x4 framing (usually 2 1/2") behind the hinge can often remedy the problem if that is the case.

With your experience, I'm sure you already are well aware of this, but it may be helpful to mention to the readers as a follow up. It's at least pretty common here in Wake Forest/Raleigh, NC.

Thanks for sharing your experience!"

- Jeremy Wrenn, Wrenn Home Improvements