Ok, I think what FAB is telling us is that the Archives of the Department of la Loire, which are located in Saint-Etienne, no long respond to mail or email requests and that one has to go physically to Saint-Etienne to obtain the research.
I have found this to be pretty much true of French archives in general. It's amazing in a digital age that this still exists but it does. The birth record for my youngest son born in Brussels in Ixelle were still written by longhand in a great book. UK has digitized most of its newspapers and records; you have to pay to get access but you can do it. France - not so much.
However, I would like to test it. I'd like to pick one of BBS's Robusts, perhaps that of Greybeardtmm3 - Robust, model 226, SN 184688 - since he was the poster who got me interested in the subject. Then I'd write to the Loire Archives and see what happens. Would that be ok GB?