anderson gliding door

I have a customer that has an anderson gliding door. The door was very hard to operate. I was able to remove the door and inspect the rollers, it appears that one wheel on the front tandem rooler set has come free from the bearing. I did not look real hard on how to remove the roller set because I new I need to order a new. Could you advise as to how to remove the rollers. It has an adjustment screw on the inside of the door I assume this would be part of the rooler unit as well. Does it just pop out and the new pop in? I was able to clean the roolers and track and the unit does slide better but not as it should. I plan to replace all the rollers.