At some point VW redesigned the switch and cam to solve this problem. If you get a replacement switch you also need the cam. Usually the throttle not closing consistently is due a problem in the cable or linkage or the throttle stop is not properly adjusted. The stop needs to be adjusted so that the throttle plate does not close far enough to jam or bind in the bore. 
 
Dennis
 
> Date: Thu, 15 Aug 2013 07:09:14 -0700
> From: markmcculley@GMAIL.COM
> Subject: throttle body rebuild
> To: vanagon@GERRY.VANAGON.COM
> 
> My throttle body is pretty much shot and I'm tired of messing with the TPS
> to get it switch at idle. Because of the wear in the bushings the throttle
> plate doesn't always return to the same position so I have to set the TPS
> to switch a bit above the idle position. Works some of the time...
> 
> So... I see that Go Westy offers a rebuilt throttle body with ball bearings
> for the shaft, new throttle plate, with TPS, all adjusted and ready to go.
> Not too bad at $250 if it's a quality rebuild. Does anyone have any
> experience with this product or know of any better options? I have a spare
> that I could send to be rebuilt if I knew where to send it...
> 
> -Mark
> 87 Syncro Westy