sorry I just found this post here in Apr 2020 because I have a smoke generator problem with the same engine. I had the same problem as you and there was a guy named Martin Derouin who fixed my problem for me. The speaker chirped on startup but that was it. Martin "lucky for me" lived about 3 miles from my house. It turned out it was the glued sending unit that to roller sent the signal to above the axle of the wheels. I'm glad he did it for me because it was a tedious job watching him dig out the old unit and glue in the new one. By the way we live in South East Michigan. I will assume that after 2 years you either got it fixed or just gave up on it.
I need to know how the cup in the smoke generator goes back in with the spring in the cup facing up or the spring in the cup facing down on the pumper lever, ANY IDEA??? I'm going to put that out there if I can't figure it out myself. It appears in the picture that the cup is up and the spring is inside the cup.
