Probably from some guys who have only one or two. If they exist at all, they are called distributors. You can sometimes find them on the manufacturer's website. If not, then you need to rundown the name of a main line distributor that carries the line. Last but not least is good old reliable eBay.
Repairing digger... and there is one "big" stepper motor for automatic giving power to the "shovel"... and driver for this stepper is SS2B003; the signal lines are OK.