The Minnesotas were made by Davis or National I think, not by Singer. They were sold by Sears.
Photos will go a long way to identifying the machine.
Sounds like a wonderful machine to make a home for, just in case your Aunt downsizes sooner than later.
Here's a Minnesota Model B by Davis:
[ATTACH=CONFIG]511839[/ATTACH]
This one started off in life as a treadle machine. It was converted to electric and put in a home made base decades ago.
Hope you get your Minnesota, they're nice machines.
Joe