Can you please upload a few pics of how you have the inside setup. Closeups of the Flame Zone setup would help. Also, this may sound weird, but a closeup or two of the grease channel that surrounds the Flame Zone setup (the channel that takes all of the grease down to the grease chute). Also, please take your Flame Zone setup out of your MAK and take a pic of the underside. I had the same issue with grease leaking when I bought my 2 Star back in March of 2017. Want to see if it looks like the same thing.
One thing I have noticed is that this if you use foil or an aluminum loaf pan to line tHe grease tray, you have to very careful that the foil is perfectly even with the edge. What I mean is that the slot allowing the grease to flow into the tray “guides” the grease along that very front edge, the one that the locking screw is on. I had a crimp in mine at that edge and the grease flowed under the foil, albeit still in the tray.
No foil on the drip pan. Did put foil over the top of the flamezone but only to the edges. Will take a photo when the cook is done. Grease is running down the side of the drip pan. There is a little vertical play in the drip pan with the screw torqued snug.
Without pictures of the grease chute from the vantage point of inside the firebox I'd say try not sliding the grease catcher all the way in, Try sliding it out about a 1/2" out from it being all the way in and see if that temporarily solves the issue. For a more permanent solution you may need to call MAK customer service.
Has it done this from the beginning? If no then what have you done differently before the leaking started?
That is strange, try to make sure the grill is on a level surface. Also try not tightening the nut down just leave it loose like scooter suggested to see if it is pushing the grease box up (its only there to keep the box from jiggling out when you roll it, not as a seal).