Sorry, deleted my lengthy inquiry but for some reason could not delete the thread.
Publicly available, we have the incredibly useful MRN pdf files from the early 1960s to 1972 (Volume 12). Then we have two 1981 issues (Volume 22), then another big gap to 1992-1994 (Volumes 32-34, one issue each), then finally a single Volume 37. My post was about all the missing volumes 13-21, etc. from 20+ years of MRN publication that were not available to us as pdfs - and couldn't we fix that.
In reading the 1992 issue, I found that the first article was something to the effect that MRN was back - after 20 years, that gap having to do with management, priorities, etc. So I started to think that many of the gaps in MRN availability may be in fact due to non-publication rather than lack of anyone coming forward with paper copies, scanning and uploading, etc. It never occurred to me that MRN would keep advancing the Volume number for years it was not published!
But yes, there may be other gaps that can be filled, in the 1960s-1972 period, or later on. I'm just not sure.