Not a Kubota guy but its either the tach cable, where the cable goes into the back of the cluster is stripped or the tach drive which should be located near the front on the block, if you get a new tach cable and it breaks again when you start it, you know its the tach drive
Do some tractors have separate tachometers? One for engine RPM's and one for PTO RPM's? I've only seen tractors with a single engine tachometer with a printed mark or pointer that usually is labeled PTO or 540 PTO.
All the new John Deere and Kuhn round balers come with a speed sensor located right next to the clutch on the pto shaft of the implement which can tell you PTO RPM on your monitor, pretty neat stuff, depends on the implement I suppose! As far as it coming standard on any tractors, I never get to see anything new anymore so im not sure
The Kubota Grand L tractors with Intellipanel show ground speed, hours, trip hours, RPM and PTO RPM.
No tach cable on the L3130 it is an Intellipanel with speed sensors on engine and transmission, temp sensors on engine and transmission, and switches on everything, some place there is a switch that lets the Intellipanel that the PTO is engaged, the other morning when I started brush hogging mine was saying 0 RPM no PTO and a few minutes later it started working and was showing the PTO RPM so somewhere I have a dirty switch.