The solution of this problem I've come up with is as follows:
look for something what you can use as spacer.For example a metal pin which has roughly the same dimensions as the original pin(I mean the axis of the clip) but is shorter in so far that it doesn't reach over the limits of the metal assembly where the pin goes in.Or you use two little pins which are long enough two hold the spring together with the metalframe.Then you can assemble the spring with the metal frame/holder just like it's supposed to be but without the clip yet,then put the clip on,hold/secure it in the correct position by one hand and push the "dummypin" out by pushing in the original pin from one side.Maybe it's a bit fiddeling,but in the end it works.
Sorry for the cumberstone description,I hope you can understand it good enough.For more complex things then day by day chatting my english is to limited

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Greetz,Alex