Older Z Spar Furling line replacement

[wscotterwin]

Hi All,
I have a 28 year old Z Spar mast that has the Main furling system. It is not clear to me how to replace the furling line. The line goes into the mast, into the rolling drum and I assume held internally with a knot in the end of the line.

With the limited access to the drum through small access ports (Drum system NOT removable unless the mast is pulled) I can't see where to access the knot.

Does anyone have one of these an has done this? I will try to attache some pics.

[wscotterwin]

Mast Pics