This ethnographic study investigates maintenance and repair practices that underpin the data work of French cancer registries (CR) amid transformations in healthcare data governance driven by France’s national AI strategy. CRs’ mission is to provide high-quality data to assess public health policies. Through three cases of breakdown, we analyse repair practices in relation to the regime of knowing—encompassing practices, value schemes, and authority arrangements. Drawing on this lens, our empirical study extends repair studies by showing how care, expertise and power relations are intertwined within CRs’ repair work. When faced with governance transformations, our findings show how CRs resist these shifts and seek to maintain the regime of knowing to sustain their legitimacy within the healthcare data infrastructure. The study highlights how CRs’ restoration efforts seem to fail and points to the need for CRs to move beyond repair to preserve domain-specific knowledge and public health values.