I realize this is an old thread, but I was searching for information on the Sandstrom Banjo Ukulele and found this.
I have one that belonged to my Grandfather. He lived in Oakland in the 1920's-1940's, so it makes sense that he'd be in the right area at the right time to get one. He was a multi-instrument musician and I know the banjo ukulele was very popular back then.
It's in original condition with no damage other than a little wear from playing. It has the original case and even found some original replacement strings tucked inside.
I replaced the strings with modern nylon ones and it's back in business. It's hard to keep tuned with the skin resonator and the bridge moving around so easily. I love to play it with older songs from that era ("Yes sir that's my Baby", and "California Here I come", etc.)
-Jamie