I have a machine with a dying hard drive - bad sectors are starting to multiply :-(

The first sign (24 hours ago) was that it had an unmountable boot volume. At this time, I tried booting to safe mode with command prompt, which worked, after which I rebooted normally and ran a chkdsk. It has since been working as well as I could expect, but slowly getting less reliable. So I scheduled another chkdsk on both partitions (C: - boot, D: - data), having freed up a lot of space on both partitions to give Windows a little more scope for repairs (hopefully?). I then rebooted.

On reboot, it protested about the unmountable boot volume again, so I booted to safe mode. I got the same list of drivers loaded as yesterday, and then no change to the screen for the past 2 hours. However, I see a flickering hard drive indicator light - not always on, but seldom ever off. What is happening? Is the chkdsk that runs in safe mode one which produces nothing on the screen and so chkdsk could be doing its thing... or is Windows still trying (but failing) to boot into Safe Mode?