Think of fire management 101. If you set it high, it dumps a lot of pellets trying to get to that temp. What happens is that if you clean the pot, you're suffocating the fire before it starts.
So pellet overflow is either that or a bad ignitor.
That's why I throw a handful of pellets in to start, get the fire going quickly, but I like the low temperature start idea BUT if it doesn't feed enough pellets, it might not start (just wanted to say that in case you get one where it doesn't start)
Always a little learning curve, but CS Customer Service is the best.
You post/question is perfect, I'm getting my CB in the spring after I get my deck finished.