That is one of the most beautiful cabinets I have ever seen, really. Beautiful finish.
Can you post pictures of the numbers on that little Singer needle box? I have some old needles and we might get lucky.
As far as the belt, you wouldn't buy a vintage car in need of a replacement fan belt and park it because you didn't want to change the belt, would you? Well, ok then. It's super easy to change the belt. I bought a 2 pack off Amazon for my White Rotary and just reused the metal staple from the old one. There's a space about 1/8" or 3/16" wideb the ends because I kind of flubbed it. It works just fine, though, so I'm going with Winner, Winner Chicken Dinner as the outcome. So, change that belt and get Bessie back inn the saddle again. Her history isn't done being made yet- her chapter with you and your wife still needs to be written.