The Blu-Ray diode is blown. With a healthy laser when the disk is seated by the load mechinism the laser will power on a bright purple beam at first and start spinning the disk if one is detected. If it doesn't detect Blu-Ray media then it turns to the standard laser (red) and it will bounce up and down a few times trying to focus. You need good ol part number KES-400A which is a new laser.
Originally I drew the same conclusion you did and wasted a bunch of money on the part KEM-400AAA which is the whole laser and spin assembly. You don't need all that. Just get a good laser and carefully install it and you should be good to go. Be very careful installing it though as it is VERY susceptible to Electrostatic Discharge. There are only a few sellers that have this part. the best thing to do is go to ebay and type in the part number. But beware, make sure they have a guarantee on them. I just bought 5 of them and not one works properly. There is one seller http://myworld.ebay.com/jimmyestore he is a little more expensive, but at least the lasers work!! Good luck!!