The Lumbar Support Pad on two Aeron Chairs failed within the first year. The foam at each end of the pad splits and the result is the pad kinks where the split occurs. Found both new and used replacements available. New replacements are $40 - $70 on ebay. However, reviews of the replacements indicated dissatisfaction due to a repeat of the same failure.
One post reported repairing the Lumbar Pad with Gorilla Glue. Tried this approach and, so far, the fix has worked fine. Peal back the split portion of the pad on both sides of the plastic attachment points. Wet the entire area, including the split in the foam. Apply Gorilla Glue to both sides of the entire exposed area. Clamp tightly and use electrical tape to draw the split foam tightly together. Leave overnight to cure. Gorilla Glue expands, so it will likely be bulging out of the seams the next day. Use a sharp serrated knife to cut away excess glue. Use a black permanent marker to color any remaining visible glue. Repair is not visible when installed and functions as new.