The answer kind of depends on what has caused the stall. Is your wort actually fermentable beyond that point? Was the yeast healthy? Are your measurements correct? If the problem is a wort problem, then adding yeast will not help, unless it is a diastatic yeast. You could add an enzyme in this case, to continue converting the wort. If you pitched enough healthy yeast, it's unlikely that racking to secondary before primary had actually finished would be problematic, though I would usually wait until I got a LOT closer to terminal before racking.
70 F is maybe a little warmer than I would do, but shouldn't have caused your problem. My best guess would be a wort issue, or you simply rushed primary. Adding more 1056 is unlikely to hurt, but may not help that much either. I'd say give it a burl.
I'm a little confused about your timeline - did you do primary for 4 or 6 days? Do you mean that for 4 days the airlock was bubbling, then it wasn't for 2 days, then you racked?