This forum from ESRI allows a space to discuss and troubleshoot the free ArcGIS Census Tools extension that can be used for the LUCA and BAS program.
Lost your user guide? Download one here
This number will direct you to LUCA staff at the Census regional office in Chicago to help answer questions about LUCA in general.
This number will direct you to staff in the geographic partnership division of the Census Bureau. These are the experts who can help talk you through any technical problems you're experiencing during LUCA.