[spdbrake]

Def your booster then.
Unfortunately the atmospheric vacuum vent is inside the booster or could be the main return spring.
AGCO Automotive Repair Service - Baton Rouge, LA - Detailed Auto Topics - Vacuum Brake Boosters
http://images.thesamba.com/vw/gallery/pix/1246835.jpg

http://repairguide.autozone.com/znet...528004b46b.gif

https://www.abqjournal.com/551155/fa...rake-lock.html