Heidenhain EnDat

Hi

What are the rules for choosing a heidenhain EnDat encoder?

I have a broken encoder on my Baumuller servo motor need to be replaced, Apparently the encoder model is outdated (ECN 1313), and you could not find it in the market, Somebody told me you need to find an ECN 1313 with the same ID Nr and with the same secret code next to the model like G5 or V1 ...

Any idea?

Best regards
James