I know it's frustrating, but don't suffer in silence. Email you problems to S&W customer service. They'll email you a shipping label to return the firearm (at their expense) for warranty repair.

I doubt they'll do anything about loosening screws (you just need to check them before/after each shooting session).

I have a 4 1/4" 66-8 that has the same config "gas shield". Maybe S&W has a fix for the debris buildup but I doubt it. I've got over 3,000 rnd thru mine and have never dissasembled the cyl/yoke for cleaning. I just put a drop or two of clp on that area before shooting and if it starts getting a bit balky.

They should be able to fix the other problems.

FWIW,

Paul