I own a a 659 that I bought new in 1985. I've shot it a lot over the years. It was worn to the point that the hammer would not drop when the decocker was used. If I put the safety lever down and then pushed the slide down then the lever that releases the hammer would make it drop.Of course the safety worked since it just rotates to block the hammer. Back in Feb I sent it to the factory for this and the old recall where the hammer would not drop from half cock. They called and told me the gun was worn out and they could give me a credit towards a new gun or just send it back to me. I had them send it back.
I got to looking at what made the hammer fall when decocking and figured out it was the "sear release lever". Bought one from Numrich for $3.98 and it's all fixed now. The decocker even works from the half cock position, which it never has. I'm happy but I don't know why the factory couldn't fix it.

That's interesting. About 3 months ago I sent them a 1066 with the same problem, decocker not working. They repaired the gun and returned it to me at no charge.

I think different calls on different days might get different results.

Interesting that S&W did offer a credit as a 1985 pistol predates their lifetime warranty.