My speedometer cable broke, so I replaced it, housing cable and all. For about a week, the speedo worked fine, but has recently become erratic. At highway speed it will waffle plus or minus 10 mph. It settles down to zero when stopped. The cable is well lubed with lube which came with the cable. I pulled the cable and housing apart, and there are no tight bends or flaws in the assembly. With the speedo on the bench, the shaft into the speedo head turns freely and the worm gear which operates the odometer turns freely. I read the archives and learned about the spinning magnet which turns the needle. If I clean the head with WD 40 or brake cleaner, will that affect the spinning magnet's operation? Also, should the head be cleaned with compressed air? The spring which is visible looks too frail to stand up to an air jet. Thanks in advance for suggestions
