[Hampshire] disk cloning problem

I'm trying to use "dd" to clone my laptop HD to a larger one. But so far I
have had only partial success. It copies four out of six partitions, but
ends with the error "dd: reading '/dev/sda' : Input/output error". The
device in this condition can't be used to boot as it comes up with a grub
error.

This looks to me to be a problem with the sda device. However, this where I
run into the brick wall, as I don't know how to check the device, or what to
do if or when I find a problem. I would welcome any advice.

Thanks,

Kelvin