It should be possible to identify the record offices which hold the original sources microfilmed by LDS. How does one do this? I have been unable to identify anything about this on the website.
I am just another 'lowly' User/Patron ...
Just in passing ...
With the FHL Film number (&/or "DGS Number), you should be able to search the 'FamilySearch' "Catalogue".
To obtain, the "Details", of where the Record, was obtained/scanned, by doing a:
Film/Fiche/Image Group Number (DGS) Search ...
I hope, that this may help/assist, somewhat.
On each page in the FamilySearch Catalog, the name of the author/record custodian and the repository where the records were stored at the time they were microfilmed are listed.
For example: https://www.familysearch.org/search/catalog/153790?availability=Family%20History%20Library
These records are by the Church of Scotland in Lesmahagow. In 1952-83 when they were microfilmed they were archived at New Register House in Edinburgh.
Do you have a specific record in mind?
I'm working in Philadelphia marriage records this morning, and the first image on each roll of digitized microfilm has this notice:
This particular item is Film # 004285105.
On some New York State marriage records I accessed over the weekend, DGS 4664868, the first image on the film is
Is that the kind of information you are seeking, @Stuart Raymond?