having trouble with the Trailtech vapour fitted on my Berg. The speedo stopped working and I cant find any problem except with the rotor magnet. The sensor mounted on the brake caliper is not sending a pulse to the unit when the magnet passes but when I try waving a large magnet that I have at the sensor I get a pulse. I'm wondering if the magnet is somehow faulty although it does still have some magnetism. Has anyone experienced such a thing?