If your sliding patio door is difficult to move or lock, it could be due to the rollers. Most patio door rollers can be adjusted to account for wear. Sometimes the rollers are so badly worn or collapsed that the aluminium door frame itself is rubbing on the track. Eventually this rubbing can also destroy the track which will add to the expense.
In the picture above you can see 2 old rollers (left) which we removed from a door in Forest of Dean today. They are pictured with a new roller for comparison. The old rollers are completely worn away ( the only bit left is the bearing). No wonder the door didn’t want to open and couldn’t be locked.
What maintenance should you do for your sliding patio door? Keep the track clean and free dirt and grit. Do NOT lubricate the track. Lubricant on the track will attract grit and encourage the rollers to skid and flat spot. You want your rollers to grip the track and rotate correctly around the bearing. It’s the same as you don’t want your car tyres skidding on oil or ice – you want them gripping the road surface and rotating around the bearing.