Unfortunately Mr. Flexor says he can't repair light meters because parts are not available. I remember that there were new parts some years back, but apparently no longer. Perhaps Germany?
I presume you are referring to the "F" and "E" versions which have selenium cells. Repair success depends on what is wrong. If the galvometer is bad (I tried to repair one with a bad 'whisker' wire to the coil and failed) you are out of luck unless you find a donor camera with a working meter. If the light cell is bad, this is repairable, but not easy.