From what I've read on here, I have had a common problem as the speedo magnet broke into three. Luckily it didn't eat through the pickup sensor. I cleaned it up and glued the broken pieces back in and for added security put heat shrink over the top. With the heat shrink on there is a tighter fit in the casing but the sensor has a reasonable gap. It's all working again but as I have a 45tooth rear sprocket the speedo isn't accurate and is in KM's but a cheap fix.