Just recently I have noticed that there is water leaking from the small screw on top of the automatic air vent attached to the pump.
It does't leak all the time and the water that does come out looks likes it's contaminated with a green oily substance.
The small screw is tight in the hole.
Would be gratefull for any help or advice?

Andy, July 2009

You need a new auto air vent as the float will be burst inside it allowing water out. The green slime suggests that the system hasn't been flushed correctly after installation, best to use chemicals to flush system, drain then add inhibitor.

Ian, July 2009