I have a brand new ppk/s 22 with the same problem and was able to figure out the issue. The top of the slide has a slot that the front edge of catches the back end of the recoil spring.
The 2nd? 3rd? recoil spring on my PPK/S 22LR is about 1mm smaller on the "back" end of the spring. That end of the spring is lapped, while the front is gapped.
FWIW. The Recoil spring on the BK Dated coded that I have has a short 90 degree bent end, on the spring where the bent end slides into a hole under the barrel shroud.
What! What! What! These springs are usually open on the end....The windings simply are wound with the ends being tight against the adjacent coil. Some springs are ground on the end to make a flush fit...usually larger diameter spring wire than shown. And if the last coil has had the end of the coil bent 90* out...that spring will only fit one way correctly. And each pistol must have a hole to accept it. If Walther changed this and your pistol does not have said hole....then the spring won't fit properly regardless of orientation. How about some good photos of the hole in question. I would not think it would be on the slide. I would think it would be on the frame boss that the barrel is fitted through.
On the PP pistols the barrel is pressed in and pinned in place. On the Umarex PPK/S the barrel is fixed to the frame in the same manner as the P22. Barrel inserted through the frame loop, barrel sleeve installed and a barrel nut tightening the parts to the frame.
Good pictures sure do help everyone understand what is being discussed. 1917