my source never gets back to me.
yesterday a friend of mine who is an audiophile and technically very knowledgeable came over to the CDSAse owner's house and help to check out what is the problem of the drive or tray scratching the disk.
He found out that the problem is due to the installation of the front part of the disk mechanism is 1-2mm lower than it should be. once he added a thin washer in the front stand up column supporting the drive, the problem is solved. I tested several new disc after this adjustment and the disc leaves no any mark on the surface.
This proves how negligence the emm Labs assembly worker is or their quality control.
Bryan