Because it stopped working last summer as efficiently as it had done previously, I stripped it down over the winter, also cleaned out all the pipework in case there was a blockage, and cleaned everything inside the pump before reassembly. No leaks, but still not as powerful as it used to be. My initial thoughts were that the brushes in the motor may be on their last legs, but it has been suggested to me that the diaphragm may be tired. I've found a diaphragm on the internet for £50, or a complete set of rubber bits for £80. I'm reluctant to pay that sort of money, when the parts may not actually need replacing, and I DO HAVE a gulper as a spare. However this Par pump has done sterling service for 25 years or so, and in a way, I've grown attached to it.