Fiamma Aqua 8 pump activates when taps are off

Hi, I have recently bought a secondhand Fiat Trigano Tribute and I find that the pump an Aqua 8 (01216C01) activates every 5 minutes for about 8 seconds despite the taps being off. I have checked for leaks around the taps and flush I have also laid paper in the bowls  to ensure the taps are not dripping. The 5 minute gap is almost to the second.

I understand there is a micro switch in the pump that can be adjusted and I wonder if anyone has experienced the problem and if so can they advise me where it is, or can suggest any answers.

Thanks HP