Shimano Nexus Inter-3 internal gear hub stuck in second gear? The situation My Shimano Nexus Inter-3 internal gear hub is stuck in second gear (it's a 3-gear hub). When I take the external cable housing apart, I can move the pin that goes inside to change gears, but the gear does not actually change anymore. Also, when the pin is fully emerged from the housing, there's still some space left between it and the lever that transfers force from the cable. The pin is still springloaded though, and seems pushed out into its extreme position. Still I suspect that it may not be coming out fully.

Questions
What kind of problem could cause these symptoms, and how would I go about fixing it? Is it even possible to open up the internal gear hub to fix this, or would I perhaps be better off not bothering and just installing a new one (which would mean reattaching all spokes)? 

I'm not 100% sure, but it seems that this is the hub I'm talking about: Shimano Nexus Inter-3 EV-SG-3C41-2330 -INTER-3 (Edit: broken link removed - this Shimano technical PDF is a close match).
It's not clear if you've already bypassed the shift mechanism and attempted to shift directly using the shift pin - at least eliminate any possibility that the shifter is the culprit.

If you're already considering purchasing a new hub, there's little harm in pulling the old one apart to see if it can be repaired.  For some reason the Shimano TechDocs for that hub is missing, but I was able to find a mirror on the Vancruisers.ca site.  Looking at that it's not obvious what might be broken and failing to engage inside.

Note that there are some fiddly bits inside these hubs, you'll want to lay out a nice big sheet of butcher paper or a towel to work on, and take pictures as you pull pieces out so you can remember how they go back together.  Keep an eye out for any bits of metal shavings or chips of metal, that's usually indicative that you'll find a broken or missing piece inside somewhere.

If you'd particularly like to avoid rebuilding the wheel, I've had success also just swapping the internals on some internal hubs.