My daughter recently bought on ebay a Singer 401a and took it to her local sew&vac store for a deep clean, because it constantly produced a nest of gopher guts after about every 12" of decent stitching. The repair guy said he would take it all apart, soak off all the accumulated years of dried oil, and put it all back together. He recommended fitting some sort of retrofit widget under the sole plate that would completely prevent gopher guts, saying this was something Singer had produced for this particular machine.
Has anybody ever heard of such a thing? DD never owned a machine before, and I am too far away to examine it myself. The repair person is the only one she can find anywhere near her neighborhood. Roberta in D