There was a flaw in the original design which flaw lifted the plane of the ecliptic away from the earth. Since the earth is a defining point in the ecliptic plane this is a clear problem. The problem is solved with the Mechano model. Here are some JPEG pictures:
The complete Mechano model. The sun is at the lower left with the earth atop the shaft. The bar which runs from the sun above the earth and to the upper right holds the planet Pluto, which in the course of a years moves a bit over a degree. For all intents and purposes, it may as well not move at all, that is, be a star. Although in the finished model the sun-pluto bar will be inclined 23.5 degrees to horizontal, here because of constraints on the Mechano parts, the angle is 45 degrees. The starting date, shown here, is December 21, the same as in the original diagram. Note that the sun is supported by the shaft on which the earth is mounted.
The following sequence shows the annual motion of the sun and Pluto about the earth. We start out in February (below, at right) when the sun has gone around about 50 degrees from where it started.
The sun is at right, with the bar to Pluto (held in Ben's hand) mounted to it. The earth is at the far left, mounted on its diurnal (daily rotation) shaft. The brass wheel on which the earth-sun shaft is fastened could be a band along the ecliptic centered on the earth similar to the way that the original sketch affixed Mercury and Venus to the sun. The only difference is that this band is inclined to the equator.
The next picture is taken on March 21, when the sun crosses the equator going north. It has gone 90 degrees since December 21.
Then comes June 21, when the sun is at its northernmost point. Note that the sun-Pluto line still runs parallel to the other pictures.
Next, September 21, when the sun has gone 270 degrees since December.
Finally, here is a close-up of the earth junction.
There is also a Windows video of the Mechano orrery. It illustrates both the yearly and the combined daily and yearly motions. Note: If the video doesn't start as soon as it's loaded (about 2.4 mbytes) click the right mouse button to display the play menu.