The pump is computer controlled and runs at other times, not just when the engine is turned off for a couple of mins. If yours does not work you will hear gurgling. Thats the red hot air trapped in your engine trying to get out. The pump gets full of carbon which makes the brushes stick and won't move down the bore. By this time they need changing. You can use any brushes you find, just re-size them with sand paper they are quite soft, and solder the wire on. The tricky bit is getting the base of the pump on as the springs for the brushes with piss you off and break your new brushes. Thats why you need to drill hole in the base and use fine wire to hold the brushes back while you put the base back on, then pull the wire out through the hole. 43sqds the man for that tip thanks.