Friend popped over with an RX02 drive and a working RT-11 floppy. The drive worked with my controller so I tried the disk in my own drive and it booted up straight away. He suggested it might be likely that all my drives were magnetically erased before I got them. I think this is quite likely. There is still one RX02 mystery though... VTserver will not dump the working disk, despite the system being able to boot from it. It's double density, so I am a bit surprised. Thanks, Aaron.