I've seen a video of a 99 going through 4 layers of denim 4 layers of us military canvas and two layers of 3mmish leather like it was paper. dread to think what a simarlar quality machine today would cost. I paid £46 with post which is a bargain with motor conversion
If it was mine I'd reglue it, carefully scrape the blue paint off if that what it is, rub down with medium wire wool and meths apply a coat of b l o allow to fully dry and apply a coat of shellac and wax applied with 0000 wire wool
My gift to myself was a 1924 singer 99k to restore and learn how to use.must have 4 full hides of full grain 10oz leather from old sofas that I've acquired
I've fitted a bathroom extractor in workshop also have window ajar also have co detector in workshop, i dont run it when I'm woodworking anyway shavings and naked flame not a good combination