You probably don't want my advice on this but when I have an ancient camera with a selenium meter that is no longer performing, I simply disregard the meter entirely and use a hand held meter. OR, if I can find someone who can replace the selenium cell, I have the meter overhauled.
It's not that difficult (or expensive) and it's far better than bodging the adjustments. ANY small modern hand-held meter (a Sekonic Twinmate L-208 is a nice, light, small one) is FAR more sensitive AND accurate than a 1950s era selenium cell in-camera meter. (You can also get one of the little clip-on meters, like the TTArtisan, for $60 new that provides convenience and ease of use...)
G