There is a three-axis adjustment to level the platter flush with the metal plate. The full service manual is on the site for Silver and Gold members, here's a peek:
You will need to remove the cartridge before you attempt this to avoid any damage.
To remove the top parts, first gently pull the rear sides of the wood surround out a little bit and then move the entire C-shaped wooden surround towards you about an inch. Then you can slide the metal plate underneath the arm, above the control panel to the right a half-inch. It will then lift out. You can proceed to remove the main metal piece surrounding the platter by pulling the front of it up a bit until it comes free. The platter itself lifts straight off, keep in mind you will lose belt the connection to the motor as a part of this process as it slips off.
As you may imagine you will have to replace both the metal plate as well as the platter itself after each height adjustment to gauge if the platter is flush...