On of my pump that running the three barrel CRAFTS set just operate unreliably, it occasionally died and require so knocking to get it going. Remove the pump from the tank and upon close inspection found that the rotor shaft has worn a lot.
Closer look that what the rotor shaft looks like below.
Bought a replacement, same rating of 2000 Liter/hour and this time I ensure that the rotor shaft is made of ceramic.
This Astro 2000 pump set me back RM 40.00, that about USD13.00. I had use this make before and on average it lasted about 3 years.
I would recommend ceramic shaft pump if you can find it, the steel shaft just can't last that long.