I was running into heat issues with the extruder stepper skipping, and while I turned down the voltage, I also created a little mount for a 40mm fan to blow on the extruder. So far, so good! Extruder sits at a cool 28-32C with the fan, and no jams yet. I kept the fan mount holes small (3mm as I recall), and drilled them out when i received the fan. The fan is a Noctua, dead quiet, and efficient. (Noctua 40x10mm A-Series Blades with AAO Frame, SSO2 Bearing Premium Retail Cooling Fan NF-A4x10) I've used these heavily in PC building, they are more expensive, but awesome fans. For wiring, I hardwired into the power leads. It needs to be on all the time anyway, so I didn't want to mess with blowing the board. I've included the dx file, so if you do update/adjust it, please share back!