Upgrading an old sub-zero 550 to a newer 650 unit

This customer had an old 550 subzero refrigerator, which had a broken drain tube in the freezer.  The best option was to upgrade her to a 650 unit which required no alterations to the kitchen cabinets. This was important because the aesthetics of the kitchen in her cabin were timeless and making new panels would have been difficult. The customer saved money and got a nice upgrade which blends seamlessly with her antique kitchen.
We keep a small inventory of units like this 600 series on hand for our long time customers. Sometimes an upgrade or replacement of the older unit is recommended.
Certified Refrigeration is a source for Factory Certified installs on new units as well!

[@jared8189]

What was wrong with the 550 that it needed replacing?