Remove 2 screws visible from the front of the printer on the right of the paper tray, securing the print mechanism to the base. One is at the bottom of a deep hole.
Remove 2 screws more to the left of the paper tray, either side of the card reader assembly. On the right of the card reader assembly there are in fact 2 screws, and for the moment you should only remove the rear-most one.
Remove 2 screws from rear of the top of the printer, which were exposed when you removed the top rear cover.