Hello, I dont have any info on your model ,but I have a GECO model 37 that Im going to make a similar post to yours on, hopefully we'll get some good new info.

 

Oh, I forgot mine shoots very well indeed, I have shot a true 1/4" 50 yrd group with redfield international sights!

 

I don't have any help on your quests, but I love my Geco 1919. Light, accurate and inexspensive. It seems they are made in Germany, as most of the google threads on the Geco come back in German. At least I think it's German.
Gobbler

 

I also have a GECO m28 and find it a well made, nicely finished gun. Maybe not quite as nice as a mauser or walther, but close. These were meant as competition for the the other German 22's of the time. Gustav Genschow & Co. produced a lot of different 22's from "boys" rifles to target guns. Some have suggested that other companies made thier guns for them, but I've never seen any solid evidence that substantiates that. BTW, the action on my gun is not as smooth or elaborate as my MAusers, but the stock is every bit as nice with nice walnut and very fine, extensive checkering.