What was found
FLT 8584, DURING FLAP RETRACTION, FLAPS STUCK AT 12 DEGREES AND LATER RETRACTED UNCOMMANDED. CREW ELECTED TO LAND IN BFF DUE TO WEATHER; COMPLETED THE FLAPS JAM CHECK LIST AND A "NO FLAP" LANDING. AN EMERGENCY WAS DECLARED. AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE COMPLIED WITH EXTENSION & RETRACTION OF WING FLAPS, OPERATIONAL TEST OF WING FLAPS, CLEANED CONTROL HANDLE SWITCH, CONNECTOR, FLAP BLOCK VALVE, ALL CHECK SATISFACTORY. AIRCRAFT RETURNED TO SERVICE. REMOVED AND REPLACED FLAP POSITION FEEDBACK UNIT AS A PRECAUTION AND RELIABILITY CONCERN.