What was found
THE ALTITUDE SELECTOR ON THE MCP WILL NOT CHANGE ALTITUDES. ACFT GROUNDED. CONFIRMED FAULT, MCP ALTITUDE NUMBERS FROZEN. PULLED AND RESET "MCP DC2" CIRCUIT BREAKER AT P6-2 PANEL, MCP ALTITUED SELECTOR WILL FUNCTION FOR A WHILE THEN FREEZES UP. REPLACED DFCS MCP AS PRECAUTION IAW AMM 22-11-34 OPS CHECKED NORMAL. ACCOMPLISHED DFCS LRU INTERFACE TEST IAW AMM 22-11-34 (GP 32), DFCS LAND VERIF TEST (GP 49) IAW AMM 22-11-00, AND HGS SENSORS TEST IAW SMM 34-36-00, OPS CHECKED NORMAL. ACFT LWMP STATUS REMAINS AT CAT3A AUTOLAND & HGS, CAT SCREW REFLECT SAME.