The hills on Senja made big demands on the brakes from time to time...
The previous fix with a nut and bolt on the yoke wire finally started to pull out under the strain.
This is plan B, which involves tying a length of elastic shock cord to the arm with the weaker spring so that it is balanced better against its stronger counterpart on the other side - anything to stop the pad rubbing on the rim. The other end of the shock cord is looped around the quick release at the axle.
I suppose the better option would be to take the spring out and see whether I can bend it into better shape, but I don't want to do that while I'm miles from the nearest bike shop. None of the shops I have found stock cantilever brake kits - Norway converted to the ubiquitous V-brake fifteen years ago.