dd on Debian 9 Stretch is failing.
 

So, over the past few weeks my internal HDD had been malfunctioning,
I decided to dd my disk to another using a disk image.

I created an Debian bootable USB and did this:

sudo -i

then after that, I did:

dd if=/dev/sda3 conv=sync,noerror bs=32M | gzip -c > /media/pi/OctanMyPassport/backup.gz

It is very slow an usually comes up with errors like: Error splicing file.

AMD E1-7010 Radeon R2 Graphics APU @ 1.5Ghz
4GB DDR3 RAM
1TB HDD TOSHIBA MQ100ABD01
2TB HDD WD MY PASSPORT WD001765AAS

Please help as my HDD is dying, 7000 sectors bad.

Use ddrescue instead of dd.

Thanks I will try it out!