Common issues to investigate
The lock keep in the frame has moved slightly
Pull sliding patio door towards lock keep in the frame with the door almost closed. Put the door into lock position and with a pencil mark on the frame where all the hook locks and dead bolts are, pull door away and check the pencil marks line up with the hole positions of the keep, if not you can adjust the keep position by slackening off the screws on the keep which are in elongated holes, adjust the keep position and re-tighten.
The door has dropped on its running mechanism
You can adjust the height of the door on its running gear by making small corrections in the rollers under the door. To do this you will find under the left or right side of the door small rollers. With a pozi (cross head or Philips) screwdriver adjust one of the screws visible on the roller wheels under the door. Adjust one side at a time, using only half turns. If you adjust too far in one direction it’s easy to take the door too high or too low. Keep doing this until your door is level and parallel with the track and all the lock components line up with the keep. Please ensure you adjust both sides or the door will slide true in the frame.
The lock mechanism is difficult to operate
If the lock mechanism is difficult to operate you should lubricate all moving parts with a light machine oil such as 3 in 1 oil. Then operate the lock mechanism from locked to open position several times to work the machine oil into the mechanism. We recommend doing this periodically to keep your doors operating smoothly and to increase the longevity of the locking mechanism.
If the cylinder is tough to operate apply graphite lock lubricant to a key, insert and work key clockwise and anti-clockwise until the cylinder moves freely once again, this may need to be done several times.
One other option is to try WD40 which is not a lubricant but helps to reduce water corrosion which can occur when small amounts of moisture enter via the keyhole over winter. WD40, which stands for water diffuser, will help to free up the lock mechanism. Once free we would then advise the use of light engineering oil to keep the parts running freely.