how do I kick start old eheim professional cannister filter

[waitaki]

Hi all
I have an older version Eheim Prof cannister filter that no longer self primes. I don't clean it out often because of this reason. Does anyone have a ideas how to get it started?
I have before poured water down the inlet pipe and have turned off the oulet but is not working this time ggrrhhh :x :x :x :x
once it starts it goes well. I have a back up filter, but I don't want to lose the bacteria in this one by leaving it too longer.
thanks for the help

[TW]

What about the good old fashioned method of sucking on the outlet tube. When I need to do this, sometimes it hasn't worked until I empty any water that is in the intake tube.

[waitaki]

Thanks tW was about to do that but it started after a bit of a rest!