In article , Marty Escarcega
says...

Anyone have a good fine feed handwheel for an M head or know where I can
look?

There's really nothing special about that wheel except for the crossways
keyway in the end of the hub. Any-ol' wheel with about the right sized hub
should serve with a bit of file work or a slotting bit run across the end.
I think the only other thing I remember about that wheel is that it's quite
light... maybe aluminum. I think that's to prevent it from overworking the
feed from inertia if you give it too energetic a spin.

LLoyd