2 hides stuck on wire stretchers

Got a coyote and bobcat stuck on the stretchers. It's just as the faces of both that are stuck, the body and necks are completely free. Any tricks to getting them to come loose? This is the first time I've had a problem with this.

Put the head end in a vise and squeeze it.

I usually slap the hide and stretcher against a flat surface the vibration will free it up