Well after a short break, my 300T DS has come back with a bit of a polish and some work under the hood.
The bezel spring was shredded (this watch had some use before and I think the bezel had seized prior to the spring breaking). My guy replaced it, but the wear between the case and bezel meant it just popped each time it rotated. So for now it's fixed in place, unless I can find a NOS bezel for this Aubry. Don't mind, since it aint diving, but would love to get functional again. Otherwise movement serviced () and polished a bit and pressure tested - all AOK.
Got it on a Watchadoo until I get those end pieces filed to fit the modern bracelet.