Keep in mind they were up in the air for about an hour screwing with the trim, got harder and harder to keep the plane level.....the problem wasn't the jackscrew...any more then a vibration that got worse and worse from a bearing failure, or that oil temp that gets hotter and hotter, or that little whistle in the window that gets louder and louder, or that nut job in row 17 that keeps going to the bathroom and brings a package with him.
Things break, for whatever reason and the solution isn't always in the checklist or a call to dispatch.
The passengers had the wrong pilots that day and they paid for it with their lives.