[TR] TR3A speedo and tach issues

[Foster, Stan (HP IT)]

The tachometer and speedo in my recently acquired TR3A are both reading silly
values despite new cables. The tach is reading 3000+ rpm at idle and the
speedo is reading 60+ when I doubt that I am doing more than 40mph. I'm used
to gauges needing calibrating (the car has 165/15 tires so I don't thing that
is the cause of the speedo issues) and gauges failing outright but I have not
experienced this kind of failure where the gauges are reading wildly high. Is
there anything I could do before I just pull them out and send them to someone
to diagnose and repair ?

Stan