With you MES30 you could turn on the heat at 100 for a short while to get the draft started, say 15-30 minutes.
Once the smoker is drafting, shut off the heat and the heat from the
AMNPS should keep the box drafting.
If you continue to have trouble, you might want to consider putting a stack on it.
I just finished mine today and it had no trouble at all staying lit and completely burning
all the pellets during my initial test.
Best burn I've gotten. But I did leave my heat on at 100.
Tomorrow I plan to warm it, then shut off the box heat and see how it does with just natural draft.
If you'd like to see how I attached the 3" to the damper I can take some pictures and post them.
Why most smoker don't come with a stack, or a stack option, is beyond me. It gets the smoke up and away from you and the control.