Amelia,
I cleaned mine internally then oiled, oiled, oiled, and greased it. It was bone dry. It is noisy to a point, but all of our Singer ZZs from the 50s on up are noisier than their Japanese contemporaries. I think it's just the nature of them.
Mine is electric, but I also went for it because it can be treadled. And because it uses cams for the decorative stitches, no internal cam stack or mechanism. We have a full set + of flat cams so anything we want is basically at hand.
Some point this coming year I'll set it up in a treadle and see how it works out. But for now it's sewing away as an e-machine.
Oh, and the more you use them, the quieter they get ... to a point. They are never really quiet.
Joe