I tested it in SFM and it did not work. The bone orientation also used to work but no longer does in preview. It is now at the engineer's feet. It has the exact same setup as the video and balloonicorn. I don't know what I'm doing wrong...

I have an issue with my model: I'm making a blimp similar to the ballooncorn, and have used the exact same bone format and QC code. It doesn't work however: in preview it is at his feet and in source filmmaker it goes to his hip. The jigglebone is coming out of bip_head bone and has a jiggle_base and jiggle_1. The entire model is attached to jiggle 1.

Heres the qc code:
$jigglebone "jiggle_base" {
is_rigid {
length 500
tip_mass 15000
}

has_base_spring {
base_mass 0
stiffness 175
damping 20
left_constraint -50 50
left_friction 0
up_constraint -50 50
up_friction 0
forward_constraint -50 50
forward_friction 0
}
}