....returns from garage administering "dope slaps" with both hands alternately...
OK, forget what I said many posts ago about brass slugs with rubber tips blocking gas passages. This is true of every Jap bike I ever disassembled but I obviously underestimated the deviousness of the French!
Here is how the "choke" works. The hole into which the brass slug fits is drilled all the way through the carb body (if anyone is aware of any plug or cap for the bottom end of this hole I would like to hear about it). The diameter of the hole is stepped to a slightly smaller diameter about half way down. The brass slug is also stepped in diameter so that if you drop it in the choke opening, the step on the brass slug sets on the step in the bore. The slug is a sliding fit in the choke bore for both diameters. A hole is drilled from the engine side of the carb venturi, through the choke bore and into the float bowl. This hole passes through the choke bore larger diameter just above the step to the smaller diameter. With the slug in its lowest position, the large diameter of the slug covers these small holes on either side of choke bore. This is the choke off position. When the slug is raised by the cable, the larger diameter of the slug is raised above the through hole which is now in line with the smaller diameter of the brass slug. This creates a cavity between the small diameter of the choke bore and the large diameter of the brass slug. Vacuum in the intake causes fuel to be sucked through this cavity, around the brass slug and into the intake.
Is this prone to leakage of gas and sucking in dirt? Sure, but it is French!
Ok, now to putting yours back together.
I am fairly sure that the nylon piece you have is the piece the outer case of the cable fits into on top of the carb. Before you start you may want to verify that the cable case fits into one end of this plastic piece. Mine is different, the placement of my carb requires this piece to have a severe bend as it leaves the carb.
Using a 10 speed gear shift cable inner, thread onto the end without a nipple, the brass slug, small diameter first. Then the spring, followed by the brass washer(I think dimple down but see how it mates with the nylon cable guide and carb top). Lastly, the nylon sleeve, with the cable sheath end on last.
Assemble the choke mechanism to the carb top with the carb top between the spring and the brass washer. Install the carb top. Slip the outer cable over the inner and check for length to the choke control. If required, slide the outer back off and cut to length. Shorten the cable adjuster on the control, fit the inner cable in the cable clamp in the choke control leaving about 1/16" of play in the cable with the control in the off position.
Hope this works for you,