Yours for 15 bucks shipped.
Disclaimer: I took it apart one day to see if the diaphragm was still intact. Indeed it was...nothing wrong with the assembly. But after I put it back together the fuel flows when the switch is in the wrong position. So it still works just fine, but you can't go by what the "on/off/pri" tells you. You can remedy this by using clear fuel line or taking it apart and fixing it yourself.

The plate holding the knob in needs to be flipped 180* and put back on.The selector inside could be backwards also.The diaphram isn't the part that goes bad.The little plastic piece under the diaphram has a little rubber button under it that turns to goo and plugs the vacuum port.Here's a link to convert to non vacuum operation.

http://gstwins.com/gsboard/index.php?topic=19363.0

Just posting this info to help with the sell.

Thanks ben2go. The petcock is fixed, all the components are in working order.
Still 15 bucks for anyone who wants it.

Bummer - good deal!  I just bought a new one from the dealer for $65 

The cone shaped piece in it has a trapezoidal shaped slot in the front of it with the handle piece having a trapezoidal shaped protrusion. If you shoved the metal in the plastic with the trapezoidal piece the wrong way you probably crushed the plastic into a narrow X shape (trapezoid + trapezoid turned 180 = X) ... You can flip it and it works, but it may leak ...
I know, cos I did it that way ... more than once ...
Cool.
Buddha.