hey I just looked on eBay and saw one.. anyway I was trying to look around for you and found this out
The Fuel Pump – Is a self regulating/self priming electric pump as used on many motorcycles and small cars. The fuel pressure is very low and replacing the pump with another type is usually difficult, as the pressure is so small. The pump automatically stops running when the pressure in the downstream line to the carbs reaches a set level. IT does this via a central plunger through the middle of the pump and that breaks a contact on the end of the pump. Its vital that these contacts are kept clean and the wires are attached (they have a habit of breaking off and the contacts tend to burn up). The pump is run from the fuel controller via 2 wire plug. The contacts can be got at be removing the small crosshead screw from the rubber
boot and pulling back the boot.
I would try pulling it apart and see whats up with it.. or experiment .. who knows maybe I might be doing this soon too!