glad you asked....
 weber sells the rebuild kit on their website for like 14 bucks... HOWEVER it comes with a cheap accelerator pump diaphram that tears within a year after installing it... I know from experience... it causes gas to drip out every time you touch the gas pedal.

buy the rebuild kit, but ALSO buy the accelerator pump diaphram they sell seperately for 10 bucks.... it looks like its better quality cause it IS.

i have a weber progressive, so I JUST went through this on mine....
buy BOTH and save yourself the hassle.