Main dial on 40D not working right

I did a searh and tried removing the battery and reinstalling. I currently don't have the grip on. I was going to shoot lightning and when I turn the main dial it works some times and some times it just turns no clicking or changing of the shutter speed. I tried it in M and AV. Has been working great it just started any ideas what might be happening?

No clicking means there is some mechanical problem and it will need servicing.
However, if you hadn't mentioned that, I'd have suggested that you ensure that your power switch is in the "SUPER-ON" position; the first step after "OFF" (which isn't really off at all, but that's another story), marked "ON" disables the main dial to prevent inadvertent changes. Only the third position, marked only with a line, enables the main dial.

bummer I was afraid of that.

xarqi wrote in post #12561240
No clicking means there is some mechanical problem and it will need servicing.
However, if you hadn't mentioned that, I'd have suggested that you ensure that your power switch is in the "SUPER-ON" position; the first step after "OFF" (which isn't really off at all, but that's another story), marked "ON" disables the main dial to prevent inadvertent changes. Only the third position, marked only with a line, enables the main dial.

You are talking about the quick control dial. The main dial is the one on top which is what I assume the OP is talking about.

GregoryF wrote in post #12561274
You are talking about the quick control dial. The main dial is the one on top which is what I assume the OP is talking about.

Oops - sorry for the lapse in nomenclature.