Try changing your zoom level to 1:4, 1:8, or 1:16. Choose a zoom level where there is extra space around your image and you can see the radial filter pin. Then you can either move the filter or alter it.
Hope that helps.
If you click the photo with the zoom tool or go directly to 1:1 the cursor changes to a hand.
For example if your radial filter pin is off to the left drag the photo to the right until you see the pin in the gray area.
Tab with the H key to hide or show pins.