Zipper broke

Zipper broken already.

Zipper broke before placing the guitar inside once.

Both the original and the replacement bag had a defective zipper.

I was not jostling it or walking quickly; the bag was resting calmly on my back when the zippers failed and the bass fell

Both zippers broke.

The zipper runs around the outside seam instead of splitting down the middle of the case as some do.