hi,
I run a mechanical on my Mokes and have found the PN brand that is available through suppliers at the moment, part # 3435, is quite good as you you undo the top cap and the body and turn things so that the inlet and outlet are facing the radiator rather than the exhaust which is how they come in the box with the 'lets opposite each other. It is much like the original Goss pumps that can be re-configed and serviced.
Terry