What was found
NR 1 COMPASS SYSTEM FLAGS WOULD PERIODICALLY APPEAR WITH INSTRUMENT FAILURE LIGHT. SUBSEQUENTLY NR 2 COMPASS FLAGS APPEARED. IN ADDITION EXPERIENCED BLEED THRU AND INTERMITTENT COMMUNICATION ON NR 1 AND NR 3 COMM. FLIGHT CREW ELECTED TO RETURN TO DEPARTING STATION. REPLACED F/O DIRECTIONAL GYRO, CLEANED CONNECTORS CAPTAINS INSTRUMENT AMPLIFIER AND COMPASS INDICATOR, OPS CHECKED NORMAL IAW MM 34-00. REPLACED NR 3 COMM CONTROL PANEL AND NR 2 COMM RT, OPS CHECKED NORMAL IAW MM 23-00.