The button, however, is grayed-out and I can't seem to find what would cause this so I can fix it.
These methods migrate Joins and Relates for Layers.
When using one of the Layer or Table View methods to change the workspace path or data source of a Layer or Table View that has a join or a relate to a data source also in the new workspace, the workspace path or data source of the joined or related table needs to be updated manually by way of the user interface.
First, save the username and password information with the layers.
This set of Python functions helps you automate a number of map management and output (printing and exporting) workflows. You access this command by browsing to the folder in Arc Catalog where your map document is located and right-clicking the map document.
This option is not available for Arc Globe or Arc Scene documents.
You can immediately tell whether a layer on your map has a broken data link because it will have a red exclamation point next to its name in the table of contents, and the check box next to the layer will be unavailable.
A layer needs repairing if the data source it references has been moved, renamed, or deleted or is inaccessible for some other reason.