I’ve having an odd issue with my SRAM X9 rear shifter.

When shifting down, i.e. pulling on the cable all is good.

However, when I shift up, i.e. release tension from the cable, the cable jumps over the thing it should be being wrapped round, and a couple of gears are dropped, and it isn’t possible to shift back down.

I can sort it by simply shifting all the way up to top gear, or until the cable is back where is should be, and then shifting down again.

When all is good:

http://www.flickr.com/photos/nathanmesser/8927675171

When it’s all gone wrong:

http://www.flickr.com/photos/nathanmesser/8927677655

Has anyone ever encountered this before?
Or got any tips on how to sort it out?
I’ve tried spraying some lube in there, but that didn’t help.

In case anyone else ever encounters a similar problem, changing the inner gear cable sorted the problem.