As with the other issue I mentioned before, Contour Design sent me a replacement part for the faulty component. In this case it was the scroll wheel, but because the fault could be a dodgy circuit board they sent one of those as well. I’m glad they did, because the problem was caused by the aperture into which the scroll wheel’s spindle fits, having worn loose after constant use.
Once again, I can’t praise Contour’s service enough. I’m a heavy user of their products and they stand up well to the punishment I give them. This particular RollerMouse was well out of warranty, but they reacted as if it were fully protected. You can’t ask for better support than that.