Funny enough met that this week, it is a PTC fuse, there to prevent the motor burning out with overload, by switching to a higher resistance state. Not sure about replacing it, as it is likely only an OEM only part, but you can bridge it out for testing, and replace with a 130C one time thermal fuse later on. Had to make the new brushes fit, using sandpaper to make the new brushes small enough to fit the brush holders, as we could not get any that were an exact fit. 2 hours driving around, and $1 for the new ones....... now all we need to do is find a new window switch cluster, seeing as the old one got fried because of the worn brushes, though it has had somebody in there before, lots of 'rework" wires bodged in on the PCB to replace the thin traces.