rip it out & put a decent lighting controller it, (but nobodys make anything to compete with it ?)
take the cover off & walk test it (they go opaque with age
swap sensor around to see it the fault follows
work the pots back & forth to see if the lux sense are at a working level
swap a sensor with a new one
fault finding is 2 man job after hours, it cheap to put the lights on timer