Replaced the circulator on the radiant manifold due to excessive heat during operation. Upon removal, the circulator was found to be heavily contaminated with debris. The affected loop was purged, removing a mud-like substance from the line, and a new circulator was installed. System was checked for leaks and proper operation; the zone is now circulating and heating correctly. All components are operating as intended at this time. It is recommended that the entire system be fully purged at the next scheduled service.