Well, I'm definitely not missing the push rod (part 914.424.055.00). I can't see how that does the job, though, unless mine has been hopelessly mangled.
Here's a crude picture:
Click to view attachmentPress the button and the black bit (the pushrod) moves to the right. It's sprung to keep it to the left. The hooked end presses against the top of the pawl (the blue thing), which causes it to pivot (red ball), and disengage from the ratchet. That part works on mine.
When the button is released, the pushrod just moves to the left. The pawl is left to swing in the breeze.
Now, if the pushrod is supposed to also supposed to help engage the pawl against the ratchet, then it would only be able to do so if the hooked part when over the top of the pawl, so when the spring moved the pushrod back to the left, it would pull the top of the pawl with it, which would engage it against the ratchet. However, the hooked part won't go over the pawl on my setup, as the pushrod is way too short. It also wouldn't fold if this were the case, as the top of the pawl is "underneath" the top of the non-folding part of the e-brake handle, and there's not enough clearance for the hook to go over the pawl.
This has been puzzling me for 2-3 weeks now. I'm not saying you're wrong, Cap'n, I'm saying I don't understand how you can be right. The drawing in PET is even more crude than my picture, so I can't tell if my part looks like the right thing or not. The two little posts on the pushrod are stopped by a riveted pin on the folding part of the lever that keeps the pushrod from moving too far in either direction, so it doesn't look like this is some later kludge.