Hmm, hadn't thought about that. Yeah standard deore shifter. Starts at the bottom as normal. Going to bring it in now that I'm done pretending to work and see if I can either fix it or break it enough that I simply have to get a new one.
If the cable was put in when the shifter was in a middle position (rather than at the smallest-cog position) then it might be hitting a stop somehow. Seems unlikely and the indicator window should tell you if that's happening.
I took it apart, cleaned and regreased it all and it's feeling less notchy at least, though I have no idea if it has fixed anything. Thanks for the suggestions, the weekend will tell whether it worked or not!
Hmm, hadn't thought about that. Yeah standard deore shifter. Starts at the bottom as normal. Going to bring it in now that I'm done pretending to work and see if I can either fix it or break it enough that I simply have to get a new one.