Everything markieta says is correct. But this only helps if the cable end hasn't dropped out of its "holder". My 105 shifter has broken two cables. First time the shop could eventually get it out. Second time they couldn't, so they called Shimano who sent a replacement via 2-day air (less than 1 year old.) Another shop's head mechanic told me you may have to work at it a long time, but he can always get the shifter to "10th gear" so the head is visible. I think mine broke and the head became dislodged inside. Poster above explains how to get where you can see, but if the head is indeed dislodged inside, I doubt any shop will disassemble it. They will either send it to Shiman or suggest a new one. If you're having trouble getting to shift more than a few times, chances are you may be stuck. That's what kept mine from being "field repairable."