The pod involved for the center vent in my case was to the left of the vent, accessible behind the instrument panel. I bought a pod popper/diaphragm kit and repaired the pod. It was HORRIBLE to remove - I had to use a cable-operated Dremel to remove the rivet holding the arm from the glove compartment side - but I did it. Both of the internal diaphragms were rotted on mine. This is not the "by the book" method but it worked and was easier (easier....heh...).

I advise you to test ALL the pods while you are back there with a vacuum pump (one of those hand held ones is great). You do NOT want to do this type of job twice.

This is a difficult, horrible job, but the savings for a DIY'er are enormous. I am MUCH happier with my car now that it's fixed.