So here you go:

http://forums.logitech.com/t5/Logitech-G-Controllers/G940-loose-bearings/td-p/591488 (pics)

"""
After using the device for a week I decided to find a reason for a slight "play" the joystick handle has in all the directions (including a vertical one). Considering the bearing system that is used in G940 such an effect was not supposed to exist at all.
The reason was found pretty soon: as opposed to the X axis, the ball bearings on the Y axis are seated on a steel shaft with a considerable play (due to the shaft's diameter being a bit smaller than needed) which was also the reason for an additional noise during FFB operation. As long as the same behaviour was reported by a number of other G940 owners I happen to know, it looks more like a design mistake rather than a manufacturing fault.
I managed to fix the problem by putting a steel sleeve of 6 mm inner diameter, 8 mm outer diameter and 6,5 mm long on the shaft between the ball bearings, so that during the assembly the fixing screw presses the bearing/ sleeve/ bearing "sandwitch" to the shaft base. This makes the bearings work as they should, eliminating the "play" and related noise completely.
This is not supposed to encourage any G940 owners to try this modification, as it surely voids the warranty. However I do hope that Logitech team checks this matter out to fix this issue in an otherwise excellent product.
"""


No more play in stick. And noise is gone too

As you've noted, this most likely voids the warranty. That said, Logitech has discontinued the G940. I'd be interested to see any pictures you have of how this is done though.

There is lots of pictures in link , just clik.

I use that play to fly helicopters but thanks for the tip! I'm on my third set of G940 now (rudders died on the first, second overheated during FFB) this set works fine so far.

-C-

Ah, seen. Sorry, I didn't see the link.