DO NOT DO THIS - ELECTRICAL HAZARD

Testing revealed fluctuating vibrations, kind of like "speed wobbles", indicating well worn bush(es).

This can point to the rotor being forced out of line(alignment) while being mechanically stuck(the small magnet of earlier). Judging by the soft appearance of the bush(no pic sorry), I would give this theory a solid "most likely".

Prying the rotor from the housing reveals nothing further of concern. The water inside may actually provide some cooling assistance, and through the pumps design (Magnetic Drive), poses no electrical risk. This also removes the need for a shaft seal. Sound Engineering!

The video clip is a "super slo-mo" shot with a Samsung Galaxy S20FE. It shows the speeding up and slowing down of the pump. If I take the noise it makes into consideration, this is not normal. *I may obviously be wrong*