All shafts and impellers wear with time, and the crackling sound usually means cavitation (which in of itself can pit impellers). If the impeller and shaft are worn, it may be off balance, and this can also wear the volute ( the area the shaft rides in, and housing).
You can see a figure 8 carved in the housing below, causing a wobbly shaft, that wore the pump housing area below.
This wear totally ruined the pump.
I tried replacing the impeller, but it didn't help.
A worn impeller below, back when I used play sand as substrate, which eventually got in and scored the the magnet, .
Moral of the story, inspect closely, if there is general wear in all areas, sometimes repair is futile, if just an impeller or shaft, it may be worth it, but if the housing is altered, you may not want to bother.