Use a burst of compressed air on the opposite side of the diaphragm.
Go to a service station and ask to use their inside air hose with a nozzle. Remove Both hoses from the lines, not the module. Ear close to the diff. A shot of air in the hose to the Outside of the module (closest to the wheel). Should hear the clonk. If no clonk, try other hose. Try driving it. May have to roll truck a few inches to line things up and try again.
Leave hoses off until you get home.
