I agree with Cari, use the machine, and keep oiling and greasing. Sometimes using greases like Triflow can make a difference. If the gears seem to howl something awful I have added a single drop of oil with added teflon (Triflow or Finish Line Cermaic Wet Lube). As long as it doesn't seep any where else it doesn't do any damage. In
this demonstration video it comes off as rather noisy though? Regardless I would still work to minimise it. The 401 isn't very noisy at all when cleaned, oiled and greased. Go over the oil points in the manual, oil the hook and race too, and don't forget the gears under the base. If your's is a 404 it's a straight stitch only, and doesn't have all the cam and swing needle parts.
Here's another video, these are serviced machines too. I think it has to be 30 weight oil (lawn mower oil I think), SAE 30 oil should be easily found.