There are 4 allen heads that you need to get to from the rear, two each side. Turn the bars to the left and you will see the right side ones. They are in your pic, one near the red tabs, one down a few inches. Turn to the right and you can get to the left side screws.
Then there are the two on top of the nacelle. The nacelle is heavy and might drop when you release the top screws. Be prepared for that, or have an assistant.
Be careful when you replace those inside screws. The metal is soft and will easily cross thread if you are not very careful. Get them all started properly before you tighten them. Same with the top pair. Once again, an assistant is helpful to hold the assembly a touch away from the frame and in the right alignment as you position the inner screws.