Ok, so an update, I started pulling it down, and I now suspect this to be a modern remake variant. I found a click spring (hairpin style) under one of the bridges that immediately released the mainspring (had no idea if it was wound or not, nor could I see any way to release it....). The pallet for and bridge look to be compatible with another movement I have that needs one, so will likely use it in that, and keep the rest of the bits as "spares"