THIS IS WHAT I FOUND. I recently had the same problem after changing my housing for the phone. The picture appears shaken is due to its focusing mechanism. I stripped my 1520 and played around with it to find out what caused it. The camera VIBRATES like a mad dog when it is doing its work, causing the camera to see double.
All this problem could happen if your camera did not fit in its new housing properly, or falling out or not fitting into the rubber pad that sits around the housing (not the chassis), Making the camera dangling lose in the device. Think of those parts as its suspension.
After opening it up, I find it interesting the 1520 is almost built in reverse, it greatly depends on the shell to hold everything in place, not just the chassis alone. NOW, the camera has nothing around it, but only hanging off its connecting socket. It has a good 1mm - 2mm of empty space around it, and a good empty 1cm from its connection.