Pursue

hey guys, new poster here but this site has helped me with issues in the past. recently my electric speedometer was acting sporadically then stopped, as well as the odometer. found a broken drive gear which i think caused my odometer issues, replaced it and im still having issues. My question is what is the best way to diagnose the speedo issue? will 12v power to the post on the back of the unit at least make the needle jump? does it need pulsed input? is it more likely the transmission speed sensor crapped out? any information would be appreciated