OK. Got my 5 back for what is hopefully the last time, and the drum roll please...
The pop/boing is gone!
What was it? Some sort of body panels catching on each other in the front quarter panel area.
Here's what they did today: removed trim panel in the front of the mirror, tightened all fender bolts, cradle bolts, strut bolts, lower ball joint pinch bolt, caliper bracket bolt. None of that worked. On previous visits they had already tried the windshield cowl panel and an upper strut mount.
Then they removed the inner fender liner and installed foam along two panel seams and used undercoat between panels. This worked.
The pop is completely gone except when the body flexes leaving my driveway. But ALL my cars "sigh" or groan when they do that so.... I'm happy!
Total charge: $0.
Happy customer: priceless.
By the way for those who are interested, the dealer is Joe Machens Automotive Group in Columbia Missouri. They sell Mazda, Mercedes and Cadillac.
The service was excellent, the employees courteous, and they weren't happy until I was happy. What more can you ask for?
What I found most interesting is that I was treated like I was their only customer. Other dealers in town will line up people at 7:15 and then pack everyone in a van, then you'd spend the next 30-45 minutes being shuttled all over town. At Machens (Mazda), this never happened. Not once. They schedule you, you arrive to an empty bay, and usually no other customers would be in sight. Then if you need a ride, they call out their shuttle guy and the two of you pop into his mini-van and off you go. The four times I was there, I saw maybe one other service customer. I don't know why they even had a mini-van, I doubt the back seats are ever used.
Anyway, I recommend Machens Automotive Group for buying or servicing your Mazda. In this town the Machens "family" owns every brand except Honda, Chevy and Chrysler, and I can tell you that not all of the Machens dealers are the same.
These guys are a class act.