I actually reamed one of those out once, it was a giant PITA! There was also one a few years ago on some double-stack engine that came apart, so I used the Dremel to enlarge the passages as much as possible. Sometimes there's just one place that has the restriction and you can improve things by opening up that spot.
Thanks for the info, I may have to give that a look. I noticed that the S funnel is actually in two pieces held together by tiny screws. Obviously Lionel had to get creative in 2003 to get this smoke unit (8057-200) into the tight confines of this engine and feed two stacks. And due to motor spacing it could not sit directly under the stacks.
I just want to add here that I am very happy with how these Super Chuffers work. They are a nice compact board that adds great functionality to tmcc engines, and it's really nice to have them available, thanks to grj.
my first try at installing one a couple of years ago did not go well, but that was no fault of the board. The engine in question (K-Line Mike) was very tight for space and the design of the cherry switch and cam made it impossible to get it to work. That set me back on the whole concept for a while. But time heals all, and since then the two I have done recently have worked great, and I have settled on a technique that is pretty straightforward. All good.