ABC is a fine engine, I have abc and ring types. ABC are naturally tight at top of stroke. Your motor needs breaking in, that is all and do make sure all washers are there. I am not familiar with TT engines so I can not tell you about specific washer placements. I always use electric starter and spinner as I feel it is safer (and I am lazy- let's admit it OK) Worse come to worse and they are right about ABC (and they aren't) you already have it, what ya gonna do? Throw it away? Fly the dang thing after you run another 3 tanks thru it at home breaking it in. Ya got the time don't you? If your motor is tight thru entire rotation, something IS wrong/missing. Keep at it, it will come. Wanna spend some money? Don't buy engine- get electric starter and battery for it. IMHO

No double nut on 2 stroke, common on 4 stroke though