A quick thank you to everybody who's contributed to this thread - my Maxtor DiamondMax is now unbricked In case it's of any interest to anybody, I went with the CA42 cable solution - the one I ordered turned out to have 5 wires (black, white, blue, green and orange) and the USB plug could be opened to reveal a circuit board marked DKU5 but only the GND connection (black wire) was labelled. White and blue were TX and RX (not sure which way round) and to get the cable to work at all, I had to connect the black and orange wires to 2 1.5V batteries. I didn't need to connect up the ground pin on the hard drive. Presumably because I was powering the drive from the PSU in the PC that had the CA42 connected, everything would have had a common ground anyway. I put card under the head connectors, not the motor connectors. I completely removed the screw from above the head connectors and didn't bother attempting to replace it when the card was removed. Seemed like an unnecessary risk to try to get the screw back into the live PCB without it touching something it shouldn't. Initially I tried the final step without power cycling the drive as suggested in Aviko's instructions but this resulted in nothing happening as far as I could tell. After 30 minutes of waiting for a response to appear in hyperterminal, I power cycled the drive, got the prompt back up in hyperterminal and tried the final command again, this time successfully.