If you can get rid of the MDS do it. Out of four of them I have had only one run correctly and even that one is very picky as to the tank location, it's the 68. I have had three of the 58s, still have one. Two of them broke the case and muffler and this one I have will only run on the bench, not in A plane.
The carbs are such A bad design that Horizon quit selling them. With A good carb they run great but they are more work then they are worth. A good four stroke is A better choice so ask Dad to take you down and return it while you can.
You can contact Horizon and they can fill you in on all the problems they had, they aren't shy about telling you.