I recently acquired an Old Town sailing canoe. It needs a bit of repair and new canvas. The gudgeons for attaching the rudder seem to be riveted through the rear stem. I haven't spent much time looking at them, but the only solution I have at present is to drill them out and use new brass rod to make new rivets. Does anyone have other suggestions for neatly removing the gudgeons so that they can be replaced after re-canvasing?