Are the first-gen W-body power brake boosters prone to defects? Are they a common problem?   Background:   I did a search on "Booster" and got a bunch of hits; it seems the power brake boosters on the first-gen Luminas are not overly powerful--but--I don't see anyone who has claimed to fix poor stopping power with a simple booster R 'n' R. Folks upgrade to a newer, larger booster for "better" brakes, but that's not what I'm dealing with--I think.   What I'm dealing with is an extreme case.