I have been able to disassemble the mizzen roller reefing, after removing the mizzen. It appears that the shaft connecting the winch handle to the bevel gear is jammed in the housing. This housing screws into the main gear assembly, and when it jammed, the force on the winch handle unscrewed the housing completely, withdrawing the bevel gear from the main gear assembly.
With everything apart, it is now clear where to grease the mizzen furler. You can add grease from the top, where the collar that hold the foil joins the gear box assembly, and through the two small holes on the underside of the main gear assembly.
Why the winch handle shaft is jammed in its housing is not clear to me, but it is jammed very solidly. When I get access to a hex bolt screwdriver, I will try to loosen that bolt to see if I can disassemble the shaft and find the problem. Greasing this shaft probably requires disassembly as there does not appear to be an access point. I am using penetrating oil and CorrosionX to try to unbend the shaft, thus far to no avail.
I will add a picture of how the winch handle shaft screws into the main gear assembly to the album SM Mizzen Furler.
Currently in Saint Croix on the way to Antigua to haul out for hurricane season