I got my Doll & Cie 502/5 mobile Engine Circa 1925-1930 & the 517 almost 10 years ago. They only needed some dusting.
I also have an additional 517 that needs minor restoration. The boiler end cap will have to be removed to solder new threaded washers for the loose fittings. I did not have the time to tackle it yet. If a forum member is interested in it let me know. I am open to sell or trade it with a rare steam item that I do not have.
I guess all the forum members are interested - can you let us have a few pictures, please
Arnold