I've replaced motors for the original PS1's a while back (if you remember the original PSX would die after like 5,000 hours of use. I ended up tearing apart the whole thing, ordered a new motor and soldered it back into place. Basically I just found a replacement by looking up the model # on the motor. I'm not really sure about blue ray as it may be a little more technical. Basically all I can recommend is take your time. The PSX motor I dealt with had a tricky snap in clip. It's not something you should rush. I wish I could help more
There prob is a guide or two on the interwebs on PS3. It was simple for me though as it was just a 2 prong connection