What was found
AFT T/O, NOSE GEAR FAILED TO RETRACT. CYCLED GEAR TWICE, STILL STAYED DOWN. RETURNED TO MEM, NORM GEAR EXTENSION. *S/D* REMOVED AND REPLACED CANNON PLUG D-300, NOSE GEAR POS SWITCH. OPER CK NORMAL REF 727-100 WIR DIAG 32-64-01 AND 32-64-02, MM 32-61-000-0.