The Model Integrity Check option compares the links and nodes in the graphics to the Drainage and Utilities databases. It displays a list of any elements where the graphics and the databases are not synchronised, and allows you to delete them. This option should be used with caution, because it is deleting data. A good practice is to take a screen capture of the elements before you delete them, so that you can review the resulting model and recreate any elements that are needed.