I have a Little Giant pool cover pump. Itís a model APCP-1700 and itís a bit of a pricy pump, going for around $140+ online and likely $250 at a pool store.
I noticed the pump wasnít automatically starting unless I gave it a sharp tug on the output hose. It would then turn on and complete a cycle but it didnít completely pump off all the surrounding water like it used to. It seemed to short cycle.
So I opened it up and took off the float to check it out and sure enough, the float was half filled with water. The float is a hollow plastic shell with a hole in the middle, like a doughnut. The leak was micro sized and somewhere down in the center hole area. It was invisible to the eye, but if I sucked on the center hole from one side, and covered the other side of the center hole with my finger, I could draw out a few drops. That would have taken an enormous toll on my cheek muscles, to get rid of all the water. I had a hand vacuum pump meant for automotive repair and I was able to use that to get all the water out. After a half hour of pumping and shaking and repeating many dozens of times, it was mostly empty.
To seal up the leak I got a section of a green Starbucks straw (that's how you life hack in Seattle) that was the perfect size to stick down the center hole and slathered that with PVC cement Ė it kind of would act as a liner to seal any leaks. I slid that down into place to deliver glue where it was needed, let it set for a half hour, reassembled, and now the pump is working like a champ.
Iíve read a couple of posts that mention the pump is not to be left out in freezing temperatures, which Iím certain mine was, so I guess the float (and possibly other parts) are delicate in that regard. The pump was under warranty, but the cost of shipping back to Indiana and not having a pump for possibly weeks had its downsides.
Replacement floats, P/N 177344, are available from esupplydepot.com and Iíve got one on order just in case this happens again.
There's also a post here on the same topic with great pictures of the float.