Exactly. 
I have two Legacy twin stack diesels. One is the GP7 in the thread I posted on loss of speed control. Like the GP9 smoke production was lousy. While I was working the loose flywheel problem I popped off the top access panel for the smoke unit -- really easy to do. Then the fill/smoke manifold -- also easy. I blew the manifold clean of fluid with compressed air and added smoke directly to the unit stack. Replaced the manifold and the panel and it smokes like crazy. If I had known to do that with the GP9 it probably wouldn't be dead now.
For all the forum posted complaints -- "why doesn't my smoke unit work and shame on you Mr. train-maker blah blah!!" -- I don't think Lionel (and MTH) are trying to produce problematic smoke units. They are doing their best to pack lots of functionality into a small space. This squeezes the space available for the manifold creating the shallow draft angle in the case of these Legacy units.
If I can get the tech information I need I may try to submit an article abstract to a trade publication I support. Most of their articles have been pretty dry lately and this would be a fun subject.
Thanks for the replies BTW
