Jack, if you use a thin piece of rubber, like from a dishwashing glove, you should be able to get enough grip to remove the knob on top of the advance arm. If you don't get enough grip that way, gentle use of a pair of padded pliers may be necessary.
My unconventional method for cleaning the gunk was to place the camera lens-barrel down in the custard cup seen in the photo above, with the cup filled with enough naphtha (lighter fluid) to completely immerse the entire shutter assembly (remove the front element first, and de-solder the connections to the light meter sensor). Then I put the camera ontop of my stereo speakers and tuned in a techno pop/electronica station on my digital cable box and turned the bass to max. Even at low volume, this caused a constant, gentle agitation of the solvent, and gravity allowed the debris to drift to the bottom. I would exercise the shutter and aperture every know and then, and gently swab dry the shutter and aperture blades to loosen any remaining gunk, then repeat the process several times.
Once the shutter is clean, you will want to remove and clean the rear lens element as well.
