Tunze 6105 won't pulse

[acroholicreefer]

I have two tunze 6105 pumps that were purchased a little over two years ago. One pump works perfect. However, the other one does not restart after it is turned off. I have to take it out of the aquarium to restart it. At first I thought it was due to calcium build up but after a vinegar bath the pump is still having the same issue. Does anybody else have this issue and have a solution?

 

[Craig Borowski]

Which controller is it being used on? You might first try swapping the channels the two pumps are on. Also please try turning the pump on and off while disconnected from the controller to see if it will start more consistently that way. And please check that the attenuation disc is in place at the bottom of the impeller shaft. (The black part will be inside the blue part, with the black part facing up towards the impeller.) Let me know what you find...