Well, I lifted up on the inside tub/basket and it did move a little, but I"m not sure I'm qualified to determine if the movement was normal or not.
I did take several pictures of the door boot and I wonder if you guys might be right about the wear. If I can figure out how to post some pictures, perhaps you can take a look and let me know what you think. One thing I did notice was that there seemed to be more of a gap between the inner tub and the boot - from the 8-o'clock to 4 o'clock position, than near the bottom. Again, I don't know how normal/typical that might be.
If you think the boot might be the issue, I'm still not sure if it's within my capabilities.....only because I don't know what is involved. I've had the front panel off of the washer several times; to replace the drain pump and drain tubing, so I'm fine with that aspect, but I'm a little intimidated about removing / attaching the boot to the inside (outer?) tub assembly. I've obviously removed the boot from the front panel.....and other than a little trouble getting the retainer ring/spring back on, it went okay. It is about the same difficulty getting the other side attached?