The stepper driver boards are a remarkable product of modern electronics technology. However, I’ve seen some comments on other boards that folks may have released the “blue smoke genie” out of the bottle (or fried the driver chip, to say it more directly).
The particular chip in the Sumpod kit that does the stepper motor magic is an Allegro A4983. You can see all the technical details here:
While a robust chip for the size, it is subject to one particular issue – there is no overcurrent protection. That small potentiometer on the driver board is a critical adjustment — too high a setting and you will likely fry that driver chip. With too low a setting your stepper motor will either not go at all or miss steps and stall. Shorted stepper wires will smoke it quickly! This could even come from poor soldering of the header strips to the board. Also, removing a stepper motor connector while the power is on is another way to get that smoke genie appearing. I’ll be explaining this all in detail and covering how to set the potentiometer in upcoming build instructions.
There is also an updated chip from the same company that makes the A4983 — it is their A4988. This is a drop in replacement and does have overcurrent protection built in.
Pololu Electronics has it here in the same form as you received in your Sumpod kit: http://www.pololu.com/catalog/product/1182
Perhaps Richard has already changed this in kits shipped later than mine, so you might check if you have the A4988 instead.
Thus the best way to put the smoke genie back into the bottle is to replace any burned out driver boards with the newer A4988 model. This is not entirely foolproof — you can still get smoke from the A4988, but there is a better margin for success!