We had a similar squeaky seal issue after replacing the bearings and seal for our Whirlpool Duet WFW9510WW01. During the reinstall, I gave the drum a small spin by hand after I had the tub reassembled and hanging back up in the washer and got a rubber on metal squeak from the back of the drum (definitely not the front boot). More hand spinning indicated that the squeak was likely coming from the seal and was most prominent at slow speeds. I spent some considerable time looking through old posts on the forum (what a great resource!) and confirmed that having a squeaky seal right after re-install was pretty common, especially given that the new seals don't match the OEM ones perfectly. It seems like this issue goes away for most folks after a few cycles as the drum wears on the seal a bit (sometimes resulting a burning rubber smell). Nevertheless, concerned that I may not have had the seal tamped all the way down, I disassembled the tub again to have a look. I gave the seal a few more taps. My fiance thinks that it moved a bit, but I'm not so sure. Upon further inspection of the old OEM seal, I noticed that there was a lot of grease on the lips and the inner face of the seal (where it meets the base of the shaft). While I know that the FAQ states that lubricant is not necessary for the seal and may end up on clothes, the old seal had it, the new one squeaks, and we'd never had grease on our clothes before. We spread a thin layer of the old grease from the OEM seal on the face of the new seal, around the lips, and on the base plate of the shaft. As we reassembled the tub, we made sure to spin the drum periodically to make sure there was no more squeaking. Only been through two cycles so far, but we haven't had anymore squeaking from the seal and the new bearings work great.
Very appreciative of Jarrod for the videos and all who contribute to the forum. Much better to replace a few parts than to spend some serious $$$ on a professional repair, a new tub, or even worse a new machine. No reason to toss out a perfectly good washer for lack of a relatively cheap bearing.