Where can I get a motor driver "TX14207", or a substitute with instructions?

I would recommend using our 5.6 amp driver as a replacement for the TX14207 driver. Apparently, those drivers are found in the 6040 CNC routers and will not contain documentation since it is typically sold as a part of a greater assembly. Here is the link to the recommended driver: https://buildyourcnc.com/item/electronicsAndMotors-stepper-driver-6!0a