Sounds like a mechanical speedometer "cable" symptom (on "old school" cars), and that the speedometer cable needs replacement. I'm not totally exactly sure what type of speedometer input (electrical or cable) our VX's have. Perhaps someone more familiar than me will chime in with a better prognosis. Does your VX have a lot of miles on it??? Typically, only high mileage vehicles will develop this symptom over time/miles. Let us know what you eventually find out.