And then make the Eheim Mod !
Here is a little instruction
You use this on your own risk.
I will link my explanation to the photos shown on the website which aMdMaNiAc posted above (
Link).
First picture:
Open the pump by turning the frontcover in left direction. Now you can seperate the parts. On this picture you have (from left to right) the pump, the shaft for the impeller, the impeller, above the ceramic shaft with bushing and the front cover.
Be careful with the ceramic shaft, it will slightly break.
You can remove the impeller easily be pressing the white end of the shaft together.
Second and third picture:
Wrap a short stripe of teflon tape two times (or more if needed) round the shaft.
Now reinstall the impeller. It should now sit firmly on the shaft and should not be able to move.
Now reassemble the pump. Make sure that the pump is completely close.
To be sure that no air is left in the pump you can assemble it under water.
I hope this will help you.
This modification works fine for me.
Br,
MIC