If you can identify the OEM, then you might be able to find a document from them.
My BR slide was off side to side some. I was able to position it about midway....measure each side from the outside edge to the coach....disconnect one side of the gearing and then move one side to match the other.
After that, reconnect the gearing and perform a full in/out travel measuring again.
If your system is from PowerGear, they have some documents that show this procedure. I can send them if you have the PG system as they may help visualize. Good luck