I have a Puma 80. I can't get the low pressure light to switch off?

My 100e did the same, due to debris/corrosion blocking the inlet to the pressure switch. It needs removing and cleaning out if possible (mine wasn't) or replacing.
A temporary get you going fix is to disconnect one of the wires from the pressure switch, but there is no safety cutoff if the pressure drops - replace asap.

Paul Newell
May 2006