Probably so, but just to be certain about the partition table not causing it, I’d maybe try running the dd command on /dev/sdd rather than /dev/sdd1. It should be able to read a little more than the attempt to read /dev/sdd1 did. I’m not absolutely certain what happens if a partition table is invalid and has a partition that includes a region extending off the end of the hard drive, and I haven’t actually seen a dump of the partition table posted by OP. It might be that an attempt to read a partition that extends off the end of the drive gets exposed to an application as an I/O error.

I’m also a little surprised by the lack of kernel log messages. Maybe things have changed, but with all of IDE and SATA internal drives, I always got errors logged with the kernel if I/O failed on a drive, and they always referenced the drive’s device name.

I just can’t think of much higher level stuff that would cause I/O errors while trying to read at a partition level, though.

And a failing drive could also explain the freeze in Arch, the slow booting of Debian, the inability to mount the drive, and the I/O errors, so it’d explain a lot.