Replacing broken nexus 7 gear hub with second hand one My previous nexus 7 gear hub completely broke down and i decided to replace it with a second hand wheel. I took my bike apart, and used the sprocket gear of my old wheel on the new one. After that i reassembled the bicycle. I seem to have installed it correctly but whatever i do it will not shift way from first gear. I took the wheel apart again, and reinstalled the external shifting assembly but that didn't fix it. While reinstalling i noticed something that seems odd to me. It's about the part where the external shifting assembly hooks onto the gear hub. I always thought that the part that it hooks onto should have some spring like tension on it. But it doesn't. 



Three questions:
Should there be tension on the part that the external gear assembly hooks onto?  If so, is that fixable, or did i buy a lemon?

A little unrelated, but if someone happens to know i can use a nexus 7 SG7-R42 gear shifter on a nexus SG7-R46, than i would love to know that too. (I tried googling that but got nowhere.)

Any and all help is greatly appreciated!
I took my bicycle to a local bicycle shop. They unfortunately told me that it should jump back to it's original position, and that opening the hub is the only way to find out what is wrong.

The good news is that all the nexus 7 gears can work with the same gear shifter. The nexus 7 SG7-R42 gear shifter is therefor compatible with the nexus SG7-R46.