In January 2023, after years of environmental scans, interviews with stakeholders and other IR managers, and platform investigations and pilots, the UMass Amherst Libraries made the decision to migrate its IR from bepress' Digital Commons to a combination of Janeway and Atmire-hosted DSpace 7.x. We all love a good migration presentation, but for most of us, migration remains a mysterious process that's difficult to envision. In this talk, I will walk through my process of creating a migration plan for our rather large and unwieldy IR -- from interviews with IR managers who have been through migration, the beginning stages of data cleanup and standardization, and the fun -- Excel column limits! Items uploaded multiple times!--discoveries made along the way. I will also discuss how the cleanup and discoveries are shaping our IR policies moving forward.