John, it seems like time to lube the speedo cable. I have a good friend who recently retired from the Toyota corporate headquarters technical department in Torrance California. About 25 years ago he gave me some Lexus speedo lube from when they still used mechanical speedos. That stuff solves the jerky needle syndrome every time!
I use it in my '71 Dodge van that I bought new and the needle is still steady at 340,000+ on the odometer.
