Juki HZL-35Z - Manual (Page 66)

Hook filler cord (crochet thread or buttonhole twist) to the
spur and pull both ends of the cord forward under the
guide.
Sew buttonhole in the way that zig-zag stitches cover the
cord.
When completed, release the cord from foot, pull ends of
cord forward and snip off extra length.
CORDED BUTTONHOLES
ADJUSTING STITCH BALANCE
Stitch length differences in forward and reverse stitches
of the buttonhole are equalized with the buttonhole stitch
adjuster.
If the reverse stitches are too close together, turn the
adjuster slightly clockwise using a coin as illustrated; if
they are too far apart, turn anti-clockwise.
66