This is what I did on my 7140.
Took both HDs and put them in my PC using adapters ($6) so they would work on the 40pin connector and used Nortons Ghost to clone the 6gb HD (master) to the new 40gb(slave) HD. Then put the 40gb into the laptop.
Open the CD drive and carfully clean the lens with a soft cloth and alcohol, it may just be dirty. John