You are lucky, if you forced that "cord" back in the slot, without opening up the "foil slot" more.This was wedged in the slot and was difficult to push back in.
Note: The foil is the slotted tube running vertically between the swivels.
The only way to do that, properly is to lower your halyard line and start it back throughs that "foil slot" as you feed and pull up on the main Halyard.
My Sailmaker came with 3 different cord diameter "samples" to find the right size that "does not" pull out.
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Halyard Tension... (a tip from the spar maker)I think the halyard may be a little loose
There is a "sweet spot" for tension. Too tight and the upper swivel is in a bind and won't turn. Too loose and the swivel spins with the sail. It took me two tries to find that "sweet spot".
Good luck...
Jim...
PS: I talked to ZSpars expert on the phone for 30 minutes.