My Amana washer NTW4600YQ0 shakes and bangs badly at the start of the spin cycle. It settles down a little and stops banging once it gets going, but still vibrates. (I won't blame my wife, but it should be noted that it started after she washed comforters or something heavy and in general, machines fear her.)

I'm handy, but no washer expert, but I did my internet research, and tried a few things. Here's where I'm at.

After opening the top, I found two centering springs were missing; I replaced them. The washer was out of level; it has been leveled. Problem persisted.

I pulled the drive block to see if it was stripped; it was not.

Balancing ring has fluid in it.

The balancing rods look ok, and the drum bounces when I push down on it. The springs are intact, but I don't know how to check them beyond that. Can springs be intact, but weak? Is there a way to check these?

Thanks in advance for any help. I bought this very good condition washer/dryer set used a few months ago to get us by a tight spot, and they've worked great until now.