I have posted a series of photos on disassembly of the manual furler.
After doing this I would urge you to take the mainsail gearboxes (manual and electric) out and grease the top bearing at least every two years. Also install new oil seals top and bottom. Best insurance against paying for a new $800 to $1,000 part.
I'm going to try to fabricate a rubber "skirt" that will band clamp around the part above the top bearing to keep water out but still allow some air circulation. If I manage that I'll post a photo in the same directory.