Have you tried the mixture screw as this can affect small throttle mixture as well as tick over . Supa 5 carbs are now all over 40 years old and worn so standard settings are mainly only good as starting points. Most supa5’s I have set up in recent years respond best with the needle on the leanest or leanest but one position and MZ’s carb parts vary I have seen two needles marked C6 but have visually different taper and lengths and some carbs with slides marked 70 and others not marked . Most of the carbs I am talking about were 30n2-4’s but parts may been changed over the years . Could your carb be off an early ETZ as I have never seen 30n2-5 on Supa5.