It's rather more involved than you would think. I just went through this process in trying to replace my worn winding knob with a nicer looking one. The setscrew actually holds together the outer knob cylinder to the inner knob portion that has the ASA/Weston reminder dial. I would put it back in ASAP, as these things are a pain to get realigned. Don't tighten it down all the way if you plan to remove the knob.
If I remember correctly, you merely wind the knob in the direction opposite that of the winding arrow to loosen it. Make sure that you have the take up spool in and something to keep the spool from falling down. The reason is that once you remove the knob, the winding gears are exposed directly underneath the knob. If the winding spindle falls down (like it did on mine), then you'll lose contact with the clutch spring which keeps the knob from spinning backwards as you wind the film and have not completely wound the shutter. To fix this requires removal of the top cover. In my case I sent the entire mess to DAG to sort out.
So, you have been forewarned!
