Took a pic of chimney today. Want to know what you guys think of it. It seems like a lot of stuff on the inside but we re new so I don't know what to look for. It has been burning 3 weeks non stop and 12 fires on and off before that. Am burning mixed woods all 18% and under. Chimney goes straight up. Kitchen Queen 480 Cookstove. Does this need swept? What does a bad one look like? It is very fine and dusty stuff!