Hello Bietrume,
there’s no (visible) sideway movement at both of our Stridas.
But, they’re both as good as new…
I think the cup spring can’t be the reason for this movement, the spring is on the end of the right quarter of the rear axle.
(This quarter is in fact the axle of the bottom tube, not the axle of the rear wheel.)
The left half of the rear axle is the “real” wheel axle.
And the second (right) quarter is actually a left-handed thread plus a hexagon piece.
The complete rear axle is screwed in the seat tube from the left side, the bottom tube and it’s “bearing” (part nr. 100-07) secured by bolt 373, washer and cup spring.
Supposed the left-handed thread is not loose, the sideway movement might also be generated by a backlash of the right rear joint, not only the wheel-axle joint at the left side, what do you think?
Hmm, I believe you should take a look inside, maybe first at the left for the 338 part…
I’ve original axles here, if you need dimensions for comparison please let me know.