According to the overhaul manual, it is recommended that the gyromotor bearings be replaced according to the Service Bulletin level of the specified unit.
Without Service Bulletin 13, the recommended interval for overhaul is every 1000 flight hours.
With Service Bulletin 13, the recommended interval for overhaul is every 2000 flight hours.
With Service Bulletin 26, the recommended interval is overhaul is every 3000 flight hours.