First off WELCOME, and glad to see there is someone else w/ an Attack........
Ok, I'm going to assume that you have a 6" flue like it's supposed to have. This is just my first season with the Attack, so my help may be limited, however I'm a life-long wood burner, and the Attack replaced a wood boiler as the only heat source in my house.
As Maple said, what are your flue temps, they should be in the 250F+ reigion during a burn, I had a long thread on this awhile back. I get the fire going with the bypass damper open (lever out) and let the heat (and smoke) go up the chimney till the temp reading is at least 350-400F, this takes less than 10 min. with the upper door open just enough to allow the bypass to be open, this heats the flue up quickly. The flue temp is measured by pushing the ok button and the start button twice until a number appears with a little square in the upper right, this is the flue temp before the fan. About 30 min into a burn this reading should be in the 225F+ range and seems to stay in the 275-300 range with a good secondary burn. My boiler DID NOT run like this until I has 6 or so fires in it. I was very discouraged and at times wished my old NewYorker WC130 was still there, I did not howevget any water coming down my flue like you have, only condensation in the upper and lower chambers at first. The refractory may still be wet from moisture in the air and casting.
Can you get some known dry wood and try it? This may help to get things dried out and hot, the water running down your flue is not normal, and I have a very similar setup as you, only I have 4' single wall then 16' of interior 6" Class A. Keep us posted with results and questions, all so we can ask you more!
TS