There are so many types, you really need to have your old ones with you. They are a pain to get out of the door. You will lift and pull out on the lower part of the door. Usually, you have to adjust the rollers to get the door off the track. (if it was adjusted properly before)Once the door is off it's not to bad. I had a long bent phillips screwdriver to get to the adjustment screw to lower the door enough to get it off the lower track. The door will be on the front (or rear)deck to remove the rollers. Sometimes the roller that is on the track will still float when you lift the door. If that happens, you have to pry up and out on the wheel to get it off the track. If the guide is flattened or split, they make replacements that fit over the old guide. What a difference new rollers make. Lubricate everything with silicone spray before putting the door back and make sure rollers are adjusted high in the pocket before trying to put the door in or you won't clear the lower rail. Then adjust. One more trick, pry up on the door to take the weight off the roller when adjusting it downward to lift the door. Much easier. Sorry, so long winded.