I think most of the problems with the MDS engines had to do with the carburetors. They tended to make a lot of bad carbs. But the engines were OK otherwise. Some carbs can be fixed if you know what the problem is, but you may have to make new carb parts though. Otherwise you have to find a third party carb to fit and work on the engine. Perry carbs are probably the easiest to get. OS carbs would be great but they cost a lot more though, even used.