Nope, no dice on the fresh USB drive I bought. If it won't work on a totally new, unrelated drive, sure it must be something about the player - the laser itself perhaps as you mentioned?
As it was starting to feel like I was gaslighting myself (!) I got a tech-savvy friend to help me today, and go through each stage to it's eventual (failed) result. As the network method also didn't work (although my machine's IP address was recognised by Fing), it's pointing to the laser as being the single weak link. The machine plays Bluray discs, and has been fine with SACD/DVDA playback, although maybe that aspect of the machine is being problematic. I will go and test it on my TV.