you might check pump basket lid for cracks. especially with haywayd pumps, lids are known for cracking at tightening lugs from overtightening. if that doesn't work, go to big box and get yourself a drain king (hose end bladder) to fit your pump piping. with an assistant working the hose faucet, disconnect pump plumbing at first available union past pump and insert drain king. close all drain and skimmer valves. turn on faucet full force. bladder will expand and force a water stream back through pump to closed valves. if there is a leak, you should immediately see water stream from leak.