The Eddy Mark IV heat guns have two brush holders, one on each side of the heat gun housing. These brush holders contain the carbon brushes that completes the electrical circuit for the brushed motor used in all Eddy Mark IV heat guns. If you're looking down at the heat gun, the top brush holder is set in place with a set screw and also holds in place the Red flag wire coming out of the top side of the field assembly (Stator). The bottom brush holder is also set in place with a set screw and holds in place the "flag wire" that connects to one of the heat gun element wires (the wire with no connector on it) and also the white wire coming out of the cord. Those threee wires are all twisted together and held in place with an orange wire nut. I will eventually put out some videos on how to replace both of the brush holders, but until then, if you have any questions you can always call the shop at 262-633-2344.