I'm gonna watch this in case you make progress. The intex pump we have 3000 gpm was a bit stiff this morning plugging in first time this year, so took cover off,impeller off, fan off and lubed the fan side of the motor which freed up easily. Put it back on and its loud. I suspect a bearing in the motor is wining and on the way out. Did not break motor down to see if a bearing is traceable locally but thinking of just buying a higher capacity pump like you've posted.
Can't wait to get into the switching from intex fittings to this pumps fittings nightmare. Put a Hayward skimmer on it couple years ago and kinda remember a some of that puzzle.