If it was working when it was put away, time and old oil have gummed her up. Go to Sew-Classic, a bike shop, a hardware store and acquire a bottle of Tri-Flow oil a bottle of denatured alcohol and a tube of Singer or Tri-Flow grease.
Take the top off, take the nose piece off, take the bottom off, take the needle plate and slide plate off, pull the bobbin case out, remove the hand wheel and clean, clean, clean, clean. Once it's clean and freed up you can oil the dickens out of it with the Tri-Flow and grease the gears and the fiber gear on the hand wheel with Singer grease or the Tri-Flow grease, do not oil them.
I use the denatured alcohol with a tooth brush, q-tips, cotton balls or pieces of soft rag to clean everything that moves, and there is a lot that moves in those machines.
401s are oil hogs and need maintenance regularly. Without it they can gum up like yours.
Joe