How to Replace the Kirby G4 Power Cord?

High, our Kirby has died completly after falling over, checked fuse and I suspect that a connection has come adrift somewhere inside, I plan to remove the top caseing and have a look inside to see if I can see whats happened but I would also like to check the power lead, I read above that it should after removeing the secureing screw just pull out, however ours does not seem to want to do this and I dont want to force it without being sure, our model is the G4 Tech Drive and the lead enters a small oblong plastic case which is secured to the side of the main body by a single screw. I would of course welcome any other suggestains on what might be wrong with the beastie.
Steve.