After a search on the internet for a mullion replacement, I was able to find that I had the exact same problem that someone else had - which was a broken case. Therefore I was able to order a replacement case instead of a new mullion which saved a good amount of money. When I was emailed that the parts were shipped, AppliancePartsPros included a link to reviews by others on what they did to replace their faulty parts. The story submitted by Jonathan R. from Mequon, WI, on March 27, 2016, explained exactly what I needed to do to replace my broken casing. Please refer to his repair summary as it perfectly describes what to do.