Trying to sort out the feed gear system on an 8X18 Jet lathe

[yellow_cad]

When I got this 1980s Jet lathe the reversing gears were sheared so the gears were not particluarly set up for feed/screw cut. I made some new reversing gears (otherwise not available) and that part is fine but my hang up is with what Jet calls the "Feed Gear Assembly." The machine manual is very sketchy but it does show the parts clearly and I have them all. This Feed Gear Assembly is the third unit up from the lead screw and the fourth down from the spindle. The Feed Gear Assembly has three gears. The two outside gears are capable of rotating on the shaft but only one can rotate at a time since the center gear is attached to the shaft with a roll pin (which Jet considers to be a shear pin). This pin was sheared when I got the lathe. Actually, the center gear keys to an inner ring with male dogs on both faces. These dogs engage one or the other of the outside gears when the very inner shaft that they are attached to with the roll pin is pushed in or pulled out. The function is supposed to be a major change in feed speed in one position or the other.
My problem is that I cannot understand how the feed gear train works since it appears that the center gear on the Feed Gear Assembly is never meant to rotate on the shaft and when its dogs are attached to one of the outside gears then that outside gear does not rotate either. I guess the monkey wrench in the logic is why would the center gear even be a gear if it never rotates. When I set the series of gears up to mesh, all comes to a stop since the Feed Gear Assemby gears don't rotate. I must be missing something here. Any ideas would be greatly appreciated.
Thanks, Jim