1970 corvette vacuum hles...checked vacuum hoses twice checked diagrams 10 times..pulled out what little?

hair i have left...aint no corvette techs anywhere near me...For Heavens sake can anyone tell me why the wiper panel pops up when i switch the car off...wipers work fine when car is running panel up and down when wiper switch is turned on...otherwise: 1 1970 corvette for sale ..going cheap.slight vacuum problem.