We have a uPVC front door. The door's double lock mechanism unlocks and locks from inside including the main central lock. The door's double lock mechanism also unlocks and locks from outside however from the outside the central lock located in the mid section seems jammed, u can see this when the door is open and u try to turn the key, the central lock does not always turn with the key. I say not always because when u push the central lock in and with your finger a few times it can sometimes start to work with the turn of the key. Although this is only when checking when the door is open. If I closed the door and try to open again from the outside the central lock jams up again. Any ideas if this can be a quick DIY job? I'm not really clued up on locks. Currently 1 person has to be in the house at all times to open the door otherwise we will all be stuck out. We have someone coming to check tomorrow, but in case this is an easy job I just wanted to check first.