Desperate with DT80!

Hello together! As the title already says, I am so slowly really despairing with my DT. And it always ran very hard, mostly first push through, on. So, now I actually thought the problem would be solved with a new spark plug. So new ordered u built in. With the new ZK it ran also without murmuring, as from the previous usual on the first light kick. Also after the turn off, and some time wait, it still jumped well. Even the following day yet. But: Since yesterday she murmurs again again. Came only by pushing quite hard. Twitched time and again briefly, u went out promptly again. ZK times unscrewed, u was totally wet. Spark very well visible. Now again a dry candle in u she jumped in with the light kick. Also with this, used ZK she ran again yesterday perfectly. So now I definitely exclude ZK/Züdung as error! Does anyone have the same phenomenon with his moped or some helpful tip ?? The whole would not be so tragic in principle, if I didn’t have to go to the TÜV with her, it’s rather bad if you have to change the CC there. Mfg u nice we!