My 12 month old 10speed SLX shifter has developed a bit of a problem. The thumb shift button is very hard to push and will not return without me pulling it back. I've checked the cables and disconnected them so its not that, I;ve opened it up and sprayed lube in, but thats the extent of my internal fiddlings as looking at it, it looks like its a coiled spring waiting to burst forth with the slightest of hamfisted touches ie, mine.
The return shift works fine. Any ideas on a quick and easy fix ?