Well I'm selling my parts for my old PS3, and I have the part you need. It still works great, but I would consider calling Sony and asking them to repair it so that you know what's being done is being done right.
I had almost the same problem (but mine could read and play games but failed on Blu Ray movies). It ended up being a cooling problem. After I moved my system away from my reciever, the problem went away.
Just as others have stated here and elsewhere within these Forums, the 'Lens mechanism' may have to be re-adjusted/ replaced or (view thread below...
Hope this opens up a new avenue to explore, for all those who are unsure.