Ok, so i have the same problem, the thing is that i got a replacement for the impeller, but it came off too... but it was until recently that i notice that because i was not able to use my skimmer until a month ago and the guarantee is lost( i didnt use it like for one year, only tested the replacement for a few days and it was working).
If i buy back a new impeller, how can i be sure its not going to came off... it costs like 80 dollar, and im not located in the USA, so importing it is not so easy for me.
Is there a more reliable model as it seems this impeller is poorly designed (why make the base rounded instead of flat, i dont understad).