There is not much that you can get into because the mainsail furler is a sealed unit.

On hull 425 there was a standard oil seal right at the front of the furler which I didn't notice because of the leaking grease, it simply pulled out with a piece of wire, the original seal was cracked so I pressed in a new one in and the leak stopped.

Unfortunately I haven't been on the boat for one year so the details are vague but it was simple.

Like you I took the furler to machine shop to inquire how to open it up and it isn't possible, it is a sealed unit.

Br sure to tie off the mainsail foil inside the mast before you start as it will slide downwards very quickly if not secured.

Best regards,

Trevor

Sea fever of cuan

SM 425