You may want to make sure all vanes are not moving and the screws secured them are tight properly. Unfortunately there is no way to check for a foreign objects between tubs without taking it apart.

There are the breakdown diagrams and Replacement parts for FRIGIDAIRE FWT647GHS0 Frg(v0) / Front Load Washer | AppliancePartsPros.com

Gene.

Is there a repair manual available?

Hello.

I have the same exact problem. Sounds like something is bouncing around inside the drum somewhere. I'd imagine it be a bit hard for something to get in there.

Anyway, it started to get louder over time until I had to take it apart today. Turns out the bearings are shot and broken into pieces!

So you may have the same problem. Have fun, because to get anything out between the drums or to fix the bearings, you have to tear that drum out of the machine. It's a learning experience, but I was able to do it so you should not have much problem.

If you are going to do this yourself, I suggest you buy the Service Manual. I found one online for about $10. It gives you piece of mind and it told me to do a few things I would not have thought of, like laying the machine on its back when you release the springs to leave the drum on the floor.

:)