Well, don't worry: I have the same problem.
Although I get it to shift just a 0,5 mm. Probably doesn't mean anything.
I've tried everything, pushing, pulling, hitting, dropping (gave my colleagues a scare a couple of times, when it slipped and bounced off the wall). My ego gets the biggest beating, but I'm not giving up!
Keep your head in the wind and keep going till you're home!