Yes, you are right, disk seems to be ok.
As for a backup, seems the answer is maybe! Sighs
And yes as you said earlier, I removed some very old files, made some room, and managed to install grub. Said it had completed but still no boot. Not checked the grub.conf yet to see if anything is in it. Did the install to sdb. As sda is my usb boot. Really at my knowledge limit with grub.