I have a BCM 450 with the critical alarm code 12407 fan speed issue that still comes on even after replacing the Chassie fan. At first the alarm was coming every 15 mins so I replaced the chassie fan and the alarm slowed down to 1 or 2 alarms every few days at ramdom. Not sure if a patch is required or if there is something I not sure of. The system seems to work just fine except for this alarm. Any help would be greatly apperciated