Sorry conmore -haven't been much use today but taking into account that you seem to have eliminated the leaks from both the equipment pad side and the the vacuum hose, there could be something coming from the skimmer or underneath. Funnily enough, I did some research to see if I could find anything that resembled your problem and I came up with this from Whirlpool which sounds very similar if you scroll down to the last post. The guy has even put a couple of photos up as well. This could well be your culprit! I guess then the decision is to dig, let it be if your not losing water or prime and the cleaner seems to work fine or upgrade to the robot
