Classic Instruments Speedometer

[cruisinthe34]

I'm running a new Classic Instruments speed ometer with a pulse generator attached to a 700R4.

On first driving the truck, everything seemed near perfect, even the Speedo without calibrating. But at 41 miles, the speedo quit registering either speed or miles. I thought I lost a ground or something. On checking the grounds, all seemed fine. I took the truck out again and the speedo seemed okay......for about 20 miles or so then nothing.

My next step is to disconnect the pulse generator and hook it up to a drill, power the dash instruments then spin the drill to see if I get an instrument response.

Only other thoughts are whether it is dying because it hasn't been calibrated (has dip switches on the back), or someone mentioned wiring through an SN-74 .

Any input appreciated.