Vacuum Modulator & Valve
WARNING: This page does not describe the selected car, but rather 124 other vehicles, including the 1991 Chevrolet Pickup, 1991 Chevrolet Cab & Chassis, 1988 GMC Vandura Special, 1988 GMC Vandura, and 1988 GMC Value Van. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect vacuum hose from modulator stem. Remove vacuum modulator attaching screw and retainer. Remove modulator and "O" ring seal from case. Discard "O" ring. Using magnet, remove modulator valve from case bore.