RichardS-UK - 31 mins ago »
OK ... the new disk seems to be initialised but it's showing as 76% used and 24% available because it must have the OS and data from an old PC still on it.
I think it is very unlikely there will be any old data. What capacity is the hard drive? Some space is always reserved for the root user (10% ?) under Linux; also there will be separate partitions for the the timeslip buffer and the apps which will account for some of the missing space.
Before formatting it, I decided to run the Humax HDD Test. It says "Processing ... This may take a few minutes" with a spinning triangle but that's been showing for 20 minutes already. How long does this test take to run?
It took just over a minute on my 2TB drive.