@lookae that "consistent clicking sound can be heard." is your read write actuator. You would first have to make sure that you do not have a bunch of bad drives. There are adapters for the HDD to USB that you could use to check the drives outside of the iPod. Something like this https://www.amazon.com/Converter-Adapter-MK4006GAH-MK6006GAH-MK2004GAL/dp/B07FWGPT7C would work. You may also need to reinstall the firmware. You can get old versions on here https://www.davewigstone.com/downloads/apple-firmware/ipod-firmware/
Last but not least you will need a version of iTunes that supports the 1st gen.
Of course, you are using Firewire connections. Right?