SPV2 Diaphragm pump head.
This is not suitable for use with IRR-SPV4
If the pump is making a noise but not pumping water then a new pump head should rectify the problem.
If there is no noise at all then replace the whole pump with IRR-SPV2.
Changing SPV-2 pumphead.
Sometimes particles from the water supply can stop the SPV-2 pump from working properly. Assuming that there is no problem with the rest of the pump this can be rectified by replacing the pump head.
To do this remove the screws from the existing pump head, lift it off and replace with the new one. Put all the screws in loosely then gradually tighten the screws in turn until the gap between the pump head and pump body are completely closed, but do not overtighten.