Can anyone advise where to find a replacement for the VAD8041 drive in the HDRW720? Is there another make / model of drive that is compatible with this unit?

I have a friend with a Philips HDRW720 with a failed DVD drive. I verified that it is indeed the DVD drive by taking both his unit and my unit apart and temporarily swapping the DVD drives. His unit works just fine with my drive. His drive attempts to read the disk and then NO DISC appears on the screen. The drive occasionally makes some strange noises when trying to read the disc. We tried putting a known good Sony DRU500A drive into the unit, but it rejected it.