If you don' t get errors during the self test it's probably OK. Shining with a laser pointer or flashlight does not work, you need more power.
You need to connect a proper fiber with source to see if it is working. It's most likely OK, so don't scrap it, that would be a waiste
This system has probably a semiconductor laser for the interference measurement. If the laser or receiver would be bad, you would get errors during the stat-up phase of the instrument. I don' t know the 86140A, only the 86120B. The 86120B is less sensitive and has a HeNe laser.