While I used the T-model, I initially had problems with some (too many...) beans getting stuck in the exhaust around the damper valve.
When dumping the beans in the cooler at the finish of the roast, I moved the fan and the sieve and saw to that the possible stuck beans which I then shook out of the roaster with the fan turned off were separate from my "nice" beans. Those stuck beans were usually something between yellow and possibly cinnamon in color, so I gathered that they got there very early in the roast.
Now this have been discussed before, but I thought a couple of photos would come in handy for you.
Basically a T-shaped piece of cardboard, which you then bend at the top will do the trick. Use it to cover the hole to the exhaust and all the beans will go down into the roaster instead of getting cought in the damper section of the T.
(I got a bit annoyed with the top damper leaking quite severly, so I used to take the funnel off the roaster once I had charged the beans. I then put a cap (out of aluminium foil) on the top to make it leak less. I mention this because you can make something a bit more permanent with the funnel and that strip if you take it off during the roast process. It may not look "cool" but it will work better.
