Sounds like the outer cone is loose. I have a Maillard FW bouncing around somewhere, but from memory, I believe you'll need to spin off the outer cog or two to access the cone. Just leave the FW on the hub. The face of the cone should have some pin spanner holes in it. Use maybe the Park adjustable (red is the smaller pin size), or similar. The cone will be LH threaded. See if it moves - then tighten. If this causes binding, then you'll need to remove and add shims as Dale described.
Jon Schaer
Columbus, OH