What model of Valk, is it a Tourer or Standard or an Interstate? If either of the first two it can be a broken cable or cable drive on the left side of the front wheel. If an I/S, could be a problem with the drive on the front wheel or a problem with the panel itself. The cable drive for all the bikes are the same, it's the method of take-off that's different on the I/S. If either of the first two models, I'd pull the cover off the speedo and remove the cable end, then unfasten it from the front wheel and see if the cable comes out in two pieces instead of one.
Challenger beat me to the keyboard.
