I can only speak really about Actionoptics whom have repaired several old scopes for me. I had two ols Nikko Stirling 4x32 special repaired and in one they replaced the broken fine cross hair with a duplex reticle. He also repaired a 6x42 that the fast focus can stud had sheared in it. All were very reasonable cost wise.
They are currently rebuilding a 3-7x35 pecar for me and fitting a duplex reticle to that as well.