4lane,
Not sure how difficult it is to access the two different dampeners but if possible can you disconnect one and operate them to see if they return to home position repeatedly. I suspect that one of them is more like a gas strut and will not return very well and the other should repeat position.
My old Kubota BX 1850 had a strut that looks very similar to your item 31. It did nothing for position, it strictly controlled return to neutral speed of the spring linkage assembly.
Other thing not easily done is to try and measure how much movement is required to go from creeping forward to reverse. This will provide some estimate of required repeatable accuracy of the centering mechanism. I suspect that it is not much travel.
Both the damper and spring are easily accessible. I think my next step is to remove the damper from the equation since (I believe) it's sole purpose is to control the return rate of the spring. This way I can see if the spring alone brings it to neutral on it's on any better or not. At least it will give me a next step. the movement needed to eliminate the creeping is pretty minimal so here's hoping I can identify an improvement between the damper/spring.