Ddaddy
Just doing what I do
Speedo's drive me nuts. My 66 speedo worked good with an occasional needle bounce. I pulled the cable to replace the firewall grommet that Ulf sent me and it went into fits. I have pulled the core numerous times and reinstalled and lubed and now it doesn't work at all. Just a occasional jump. No clue!
Check the speedo gear in the tranny. A sticking cable strips the socket where it goes into the gear making it jump and eventually stop working.