Today a customer who I have been to on a few occasions asked me to have a look her sliding door. When I got there the handle was tied to the curtain tie holder with a belt as the door would not lock. I removed the belt tested the lock in the open position it worked Once the door was closed it would not lock then  I shut the and tilted the top towards the frame and it locked  the rear roller had dropped. On the van I have a long screw drive that reaches tbe roller I adjusted the the rollers and the door locks