Just trying to make sure I understand the problem. Do you mean it no longer "clicks" into place when you rotate it? If so, that sounds like a ball bearing issue. There is a ball bearing in there, and if it gets dislodged, it won't "click" into place any more. You can completely disassemble the switch, but you have to be careful not to lose the ball bearing (if it's not already lost). You can put the ball bearing back into place. You have to put it in the hole, then press it down (there's a spring in the hole) and hold it there while you push the switch piece back into place. You can hold it in place with a knife or small flathead screwdriver. It's not that difficult once you understand how to do it. The hardest part is trying not to lose the tiny ball bearing in the process. I lost a couple of them trying.
Oh, and it's a 2mm ball bearing. I got some online at, I think, McMaster Carr. Actually, I have about 100 of them. If you find that you need one, let me know and I'll mail you a few.