I bet that machine can be saved..Don't give up because of the rust...Today I tackled my Grandmothers Singer 3/4 model 99 that sat in a damp basement forever...all the metal parts were rusted...Today I decided to give Brasso Metal cleaner a try and removed the parts that could be removed and soaked them in it for a couple of hrs and boy did they clean up like new...After soaking the 2 hrs Use very light grade steel wool with allot of brasso on it so not to scratch up the metal and go in an up and down direction not circles.
I taped off the machine to avoid getting Brasso on the black portions to get to rusted screws etc that I could not remove and again brought them back to life...I was so happy that Grandma could be rehabed...Now it's a good oiling and I think I'll be sewing with her before I know it.
Someone told me to use car wax on the body to get the shine back into her.