At one point, a google search could find most of the VMS source, at least through VMS 5 or maybe 6. I didn't download it at the time and haven't searched since... Given the ubiquity of vms on microfiche I wasn't surprised at the time. A quick search today, though, comes up dry.
Someone uploaded what looks to be a full set of VMS V4.0 microfiche to
archive.org, but they did it in such a way that it is hundreds of separate documents instead of one cohesive collection. I guess it's in keeping with the "here it is, but not in a particularly easy to use format" idea of the microfiche distribution...
I'm not a VMS person but I do look through a lot of DEC archives in more and less above-board places and I've only ever seen VMS source up to V4.0.
-Henry