[i]This thread was “pinned” by the admin due to the importance of Bietrume’s discovery ten posts above.
Bietrume’s explanation does belong to several known Strida issues;
to name a few…[/i]
Here we have to be careful, several readers will not be able to verify what we are talking about:
Below are detailed screenshots of the exploded 5.0 drawings, this one from the owner manual 2008.pdf, identical to the drawing at this link:
http://www.strida.com/upload/Image/FAQ/exploded%20drawing%20strida%205.pdf
and that one’s from the nowadays on CD supplied Strida manual pdf or the link below:
http://www.strida.com/upload/Image/catalogue/STRIDA%20manual-0617%20revised.pdf
Well, the drawing was “enhanced”… 
(Just amazing that the recessed (!) snubber bolt 386 with its nut (!) 387 was not updated…)
For approval are here a few pics of a brandnew Strida EVO’s rear joint parts - exactly like the newer drawing - the cup spring (now 367-3) and the washer 364, there is no third “washer”.
Red arrow: Inner edge mark of the cup spring in the brushed aluminium surface of the frame.
Green arrow: Border of the silver paint, obviously was this area masked before the painting process.
The washer 364 is already deformed, outer edge marks of the cup spring are visible (red arrow).
Below, - sorry to use your pics without permission, florian - the rear area of a 3.0 Strida:
There ARE three washers!!
Could any 3.0 Strida owner please supply more info about dimensions and material of the “missing” washer 363?