75 spider tach not working

[spate75fiat124]

Any quick suggestions on where to check for inop tach? all other gauges are working. Engine runs good

[bradartigue]

Check the lead from the coil to the tachometer is connected to the coil. Check the tach ground.

[spate75fiat124]

It is the tach itself. Have a signal at the connector to the case and get RPM on test equipment at the case connector. replacement tach due in tonight and will see. If new tach works, going to take the old one apart to see if I can fin the problem by cutting a window in the case with a dremel. can always reseal case if I can fix things

[spate75fiat124]

replacement tach works great. will now explore the old one. thanks for responses.