My pump is not working, there is no pressure anymore.
A bit of air comes out on the down pump but then seems to get sucked back in on the up pump.
I have taken it apart and checked the rubber valves and they seem ok.
Anyone know how to fix?
don't use cooking oil. it will turn to a sticky nightmare in no time. a tiny bit of silicone spray on the shaft and inside the cylinder every twenty sessions will keep your pump in tip top shape.
First check that all the small black flat rubber seals on the large plunger section that allow the air to only pass through one way, are seated properly, if they are, then what djdojo says is the best solution.
D
There was an excellent fix for an ailing pump posted by "CHAP" from SA.
I tried searching for the post but it was over a year ago and I'm not sure how to search for it.
The fix involved shoving a piece of garden hose up the inside of the pump shaft.
Perhaps Chappy could chime in with the correct explanation 
Apologies for being a little flaky on the detail 
Fossil
Take it back to the shop you bought it from. There should be a 12 months warranty on it.
The garden hose fix may work if the internal shaft has come loose. Inside the pump shaft, there is another shaft (for double action pumps). If this becomes loose or the glue is old etc, the pump loses pressure. This happened with Cabrinha pumps a bit as the internal shaft was a fracion short. You may need to replace it hence the garden hose. You get to it by unscrewing the bottom plate (it'll be tight) and cutting a piece of ordinary hose just slightly longer than the existing pipe.
If all else fails, time for a new pump...
