After disassembling, soaking the wood in oil, and swedging/countersinking the mechanism, I dropped the keys in a silver tarnish dip....a minute, nothing. 10 minutes, nothing... I ended up hand polishing every key with Wrights silver polish! I have no idea why the dip didn't work, but the keys came out looking great. Then, new corks and tan leather pads.... the body parts were lightly buffed with no compound, posts and rings hand ragged with a silver polish cloth, tenons recorked, and reassembly began. The forces of neglect and age had taken their toll, but boy, am I glad I spent the couple dollars and did the work! It took about 9 hours to turn this:
Its a really nice player! The bore is .575", but has a much more open response than I expected; bright, loud, even through the registers and with good intonation. The extra hole for low F made for a fuller low end. This would be a great jazz horn for someone who likes a vintage Conn or Penzel Mueller sound - quite a surprise out of a French instrument, as they tend to sound sweeter and more intimate, in my experience.
The biggest surprise was that, in trying to research the model, I found the company still alive and well! Their website is http://martinfreres.net/ and I encourage you to check out their history and current offerings. They've been quietly building horns for over 100 years, in the shadow of the Big 3, and I plan to pay more attention to their instruments in the future....
UPDATE - turns out the Martin Freres name is actually defunct and is now a Chinese owned company...guess I can't recommend them after all:(