Yousuf Khan wrote:
[...]
I had previously suspected the IDE cables to be the culprits, so I did
change them, but that didn't help any at that time. So at that point I
began suspecting the drive itself was getting old (which it is). Looks
like now that it's going through SATA cables instead of IDE ones, that
the cables were the culprit, even with the newer IDE cables. I'm not
sure if this is endemic to IDE cables in general, or if it was just two
bad IDE cables in a row.

Yousuf Khan

Well, it is nice that the problem went away, but I frankly cannot
imagine any way an IDE cable would be responsible. Did you change or
at least unplug/replug the power connections? Bad power
connections can cause spin problems as especially old drives
draw a lot of power on spindle startup.

Arno