Depending on the quality of NAND chips use Freeze Spray (or put NR in Ziplock and freeze in water)
Every sector will still be in error, but results will be correctable.
hddguy wrote:
NAND chip K9BCG08U1A operates not at 3.3V, which NAND reader will read it at. I believe it reads at 1.8/1.9V which is why you get many errors.
What is wrong with original PCB, do you have opportunity to repair it? Post a photo of it here
This is true for some Toshiba NAND chips, I haven't seen this work for Samsung NAND.
I have 8GB donor (Samsung TLGA NAND on one side, other side is empty) but can't part with it, only one

I also have Sony Microvault 8GB w/ SM 3257EN-Q AA, uses TSOP48 NAND, but PCB is the same as yours.
I ordered it from Sony Australia's Website, perhaps you can source PCB there.