hissing brake booster

[David Sisson <dms@xxxxxxxxxxxxxxx>]

well, spiders got a new problem: the brake booster is hissing, probably a
vaccuum leak, as it causes the engine rpm to drop when the brake pedal is
depressed. 

but oddly enough, it doesn't do it all the time! 

anyone have any experience diagnosing this? i imagine i need a new booster
(as it was filled with brake fluid -- d.p.o. when i got it...) if i need a
new booster, any recommendations/advice on changing it?

thanks!

dave sisson
86 spider grad

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