If you look closely you will see a horizontal slot near the top of the Grate centered across the Grate. This slot is set at an angle that will permit a small screw driver to be inserted. Once inserted, simply apply a small amount of aft lateral pressure. If the Grate was properly printed it should just pop out and can be moved aft to expose the pellet chamber. You should test fit the grate to insure that during the printing the grate did not become oversize. If it did, you can lightly sand the excess material from the grate.