I've overhauled the mainsail furler gearboxes and I was dry-fitting them back on before I painted them when I realized that the manual furler for the mainsail foil in the mast is stuck fast. I cannot rotate it with a winch handle at all. Of course, the gearbox is not reinstalled yet so it should be free to furl the mainsail.
It is fastened to the mast with four bolts similiar to the gearbox. If I remove those it seems to me that the foil will be supported by the mainsail halyard (which is attached to the sail, with is wound around the foil). Still, I plan to take a halyard and tie it below the sail around the foil to help support the weight and keep it from moving, especially to keep it in the upper bearing.
I have not found any information on this site relative to the manual furler except for Gates Frederichs photos of his overhaul of the Mizzen furler which appears to be of very similiar construction.
If anyone has a tip on overhauling this manual gearbox please let me know.
By the way, the problem with the motorized furler turned out to be the upper bearing in the gearbox below the sail was rusted solid. The drive shaft in the gearbox was severely pitted at the upper oil seal so I had a machine shop turn it down from 30mm to 29mm which cleaned up 90% of the pitting and should give a relatively good surface for the oil seal to ride on. You can get the oil seal in 28mm which fit nicely on the shaft.
I wonder if using Corrosion-X on the drive shaft above the upper gearbox seals would help protect it? Of course a freshwater rinse after sailing would also be a good idea.