Nice thread. I've had my RW-8's (4 of them) now for 1-2 years with out problems due to shaft/bushing-bearing. One thing I do is when I clean them (1x e/o month or two), I push the end of the shaft through the bushing from the outside towards the inside of the bushing and wiggle it as I do that. It tends to push the slime/grit out of the bushing. I do this to both bushings. I also wipe the end of the shaft with a cotton cloth.
I've also found very small magnetic/metal particles stuck to either the magnet or inside the stator sleeve. Getting them off of the magnet is easy with a wet paper towel. Getting them out of the stator sleeve is a booger. But, if I don't get them out, the propeller can stick upon starting up. Once they are removed, the pumps runs fine.