1. Pulled the drawer out and lifted out the adjustable glass tray with the cracked track attached.
2. Replacement part had a couple of little round plastic stops molded in at each end of the part.
3. Part wouldn't fit in the tracks due to the molded stops.
4. Did an engineering fix by grinding down both molded stops using a very small bench grinder.
5. New [modified] track fit perfectly.
6. Parts back in the fridge.