As far as changing the roller, it should be a simple task.
I just went and looked at the 5000 we have here. You'll see two white wheels, and a D-shaped pickup roller. The D-shaped roller is what you want to change.
To change it, you'll see a little clip on the right white wheel; squeeze the little clip towards the wheel, and slide it over to the right. The D-roller will now slide out to the right, and you can replace it. Make sure the white roller locks back into place (you'll hear a little click), and you're good to go!
Just my $.02
"In order to start solving a problem, one must first identify it's owner." --Me
--Greg