I have a vacuum pump servicing the two forward heads on an 1980 61' Hat cpmy. Still learning the systems after purchasing the boat just over 2 weeks ago. Within the last 2 days the diaphram vacuum pump has started to cycle about 8 or 10 pumps every 3 minutes. I have tightened all the double clamps, hoses appear in good shape an show no visible leaks. I have listened for air leaks at both heads and below deck with out an obvious leak. Any thoughts or suggestions would be appreciated. Thank you