Tunze troubles... am I the only one?

[Delphinus]

I had some similar issues and after replacing a motor block and impeller, found that it was the power supply. I don't know if I have the wrong diode (for voltage.. you usually run them at 18 v but for wavrboxes you want 24 v and you can step them down if you want too). The new style and old style power supplies use diodes that look interchangeable but they are not the same. Not sure what the consequence is of using the wrong one. In my case the voltage output is not steady. Multimeter showed it bouncing all over the place.