Manhattan Band Instrument Co. Winner Banjo

There are a number of question marks with this Banjolele. Not that its lovely, that is without a doubt. No the first question is who originally made it? The Manhattan Band Instrument Company were a small New York based distributor who registered the name "Winner" for their Ukuleles and other chordophones, but they just added this branding to instruments made by others. Oscar Schmidt are the most likely candidates, the headstock looks right, the brackets look right and Oscar did make 12 bracket Banjoleles, but the, very narrow, neck profile and the fret markers don't look like Oscars? The rear resonator doesn't help either because that is the second and bigger question; is it original? when I took it off to see what was what inside, I could see a lot of writing on the inside of the vellum dating to 1975, (when the vellum was put on).  The notes here suggest that more work than just a new vellum was done and whoever was doing the work at the time thought this was made by Oscar Schmidt. The only thing I could see that I though might have been extra refurbishment was if the resonator and grill had been added at this time rather than in the 1920's when it was originally made? This would fit with why I have never seen another Banjolele with a resonator like this from Oscar, or anyone else, but I can't think why anyone would want to add such a large aftermarket resonator?