Most homes have multipoint locks fitted, these locks normally work by lifting the handle and then turning the key to lock. Although to most people they are the same, the wholesaler I use has approximately 164 different variations of these locks. They have various back sets, centres, and can have hook bolts, rollers, deadbolts, mushrooms or a combination. They also use varying lengths and off sets of the cylinders fitted.
If you have these types of locks fitted, most home insurance polices will specify the need to have a minimum of three locking points. Although individual companies have differing requirements and you should check your policy. So far I have not come across any policies specifying the need to have the correct length cylinder fitted. This is very important due to the amount of break ins committed by using a cylinder snapping technic, you can find examples of this on the web and you tube etc.
When these locks are fitted correctly they work well, but can have quite fragile inner mechanisms which can break and jam the lock, if put under pressure. For example having to force the handle to get the key to turn. If you are having this type of problem using the door, it is worth getting a reliable locksmith to re-align it, as this will be much easier and cheaper than waiting until it fails and having to purchase and replace the whole lock.
If the worst happens, it is possible on the newer versions to replace the gearbox, which will save you money over the cost of replacing the whole mechanism. Andy Stott Locksmiths keep a range of the most popular gearboxes in stock with prices starting from £28.00.
On a recent call out in Newbury, where one of these types of lock had failed, jamming the door in the locked position, I was able to get to site in under 30 minutes. After opening the door and removing the broken locking strip, I was able to replace the gearbox with a new one from stock on the van, re fit the strip and adjust the striking plates on the door frame ensuring the lock can be used without the need to force the handle, which had been the cause of the original failure. With parts and labour the job cost the customer £90.00, if they had called before the failure I could have realigned the striking plates and the cost would have been halved, and the old mechanism would have been less likely to break as would not have to have been continually forced.