You might what to take it apart again, just the 4 outer bolts on the motor plate (don't remove the motor from the motor plate), to see if there is any scraping on the inside of the diffuser or volute.
Are you talking about the seal:
If you put the seal in backwards, that could cause some issues.
Yep! Those are the seals I replaced. Fairly confident I got them installed in the correct orientation. I was very diligent with that part of the process. Also changed out the various o-rings internally and got them lubed.
Update: I think I found the air leak, but I'm back to square one on the motor noise.
I removed the entire pump assembly from the 2 unions that join it to the plumbing. Inspected the o-rings, lubed them up (these didn't get lubed when I put everything back together last time), and then I carefully aligned everything and hand-tightened. This had an immediate effect: the pump basket filled entirely with water, and when I turned off the pump, the full level of water remained in the basket. Previously, the basket was draining all of the water in it when I would turn off the pump, and that was with the lid staying on. I got super excited and thought I was good. But, when I turned the pump back on: the noise came back.
Here's a video demonstrating the issue:
Again, if I remove the basket lid, let the air purge, and then put the lid back on and restart the filter, it will operate totally normally. Once it turns off, it goes back to being noisy when it comes back on
unless I remove the basket lid first.
I don't understand why the pump will be running perfectly, and within the span of 20 seconds by just turning it on and off, it reverts back to being noisy. I don't mind pulling the pump apart again to double-check everything, but I don't know what to look for since the pump does have the ability to run quietly. It makes me think there's an external factor at play that I just can't figure out.
I've got a message out to a local service provider to come help, and I'll at least be able to give him some context and direciton about what's already been done. Still open to suggestions, though!