I will have to see how many such problems there are: if just a few, I can probably just delete the old source and recreate a new one:
In that case, is there a way to do that and easily update all records that point to the problem source and make them use the new source instead?
When I decided that I was determined to get my Repositories listed in my Bibliography, I learned that:
-- step one was to modify my original source template (actually, I was using the built-in Book, Basic format template)
-- that involved making a copy of the Book, Basic format template, then learning the Sentence Template Language to add my 4 new fields for repositories and places, and incorporating those fields into the Bibliography sentence
-- step three was to use that new template to create a NEW Master Source, mimicking the original (with the new info added)
-- step four was to merge the OLD Master Source into the NEW Master Source
Task accomplished !!! The new Master Source has the new revisions, and points to everywhere that the old Master Source pointed.
Do this, over and over, for thousands of old Master Sources....