It is best to use a dry lubricant, such as a Teflon-based option, for door locks. Unlike popular oil-based lubricants, dry lubricants leave a non-stick, water-repellent coating that does not attract dust, dirt, and other debris. Using an oil-based lubricant can cause these particles to build up inside the lock, making it difficult to operate or even damaging the internal mechanism. You can find dry lubricants, some of which are made specifically for locks, at most hardware stores.

Over time, latch components may wear out or get grimy, leading to this problem. First, check for dirt, dust, or debris in the latch mechanism to ensure smooth operation. Use an aerosol duster and lubricant to clean and loosen. You may also need to tighten the screws in the component, adjust the strike plate, or replace the lock. If none of these steps resolve the problem, consult a professional locksmith.

A door lock service is performed by a professional locksmith, and the cost of hiring a locksmith for these kinds of repair tasks usually runs in the $100 to $250 range. It all depends on the type of locks you have, how many locks are included in the service, and where your home is located. Always choose reliable, trustworthy locksmiths, and get a few quotes before making your choice. 

Rekeying is typically cheaper than replacing locks. Professional rekeying costs between $40 and $160, sometimes with an additional fee of $15 to $40 per lock. A locksmith's hourly rate averages around $75. If you do it yourself, a rekeying kit can cost as little as $10. In contrast, replacing a lock costs between $130 and $500, with an average of around $315, depending on the hardware and lock type. Rekeying is a simpler process that changes the key for your existing lock without replacing the hardware. It is a good option if you have a quality lock that works well, you've recently moved, you've lost a key, or you need a quick security upgrade. The best choice depends on the condition of your current locks.