What was found
CRUISE FL 340 CAPTS FIRE WARNING CUBE SHOWED A SUBTLE GLOW A COUPLE OF TIMES (F/O'S DID NOT) NO OTHER FIRE INDICATIONS. LIGHT DID NOT GLOW AGAIN THEN S/O NOTICED A STEADY LIGHT IN THE APU HANDLE, (APU OFF) PULLED HANDLE, LIGHT REMAINED. DISCHARGED AGENT, LIGHT REMAINED. DECLARED EMERGENCY DIVERSION. ACN RELEASED FOR SERVICE PER MEL/CDL: 26-11-B CATEGORY: C EXPIRATION: 06JAN07. REMOVED AND REPLACED RELAY R175. REPLACED APU FIRE EXTINGUISHER BOTTLE PER AMM 26-23-001-4.