Wadia 301 cannot read disk

I posted a thread a while back about this player which I thought was skipping. I have had the transport checked by a tech who is absolutley sure that the transport is ok. On certain disks it is unable to read any data - it normally reads initial data and displays the total disk time. However, in these cases, it either reads nothing and simply won't play or it starts to play and then keeps going back about 5 or 6 seconds. It doesn't happen on every disk, but always happens on the same disks. Some of the CD's are brand new so it isn't scratched disks. I tried some really old scratched ones and it plays these just fine. I am starting to think it might be a problem with the firmware. Any ideas? A lot of the disks come from the same manufacturer. Please don't suggest going to Wadia - they have ignored my previous 2 emails. I would publicly like to thank Steve at GNS for taking the time to reply.

Many thanks