I have a Briggs Quantum 6.5 hp pushmower that will not restart when hot. It's for a customer. Prime the mower (cold) 2-3 times, and it starts on the first pull. Mow for 30 minutes, shut down to empty the bag. Empty the bag, put it back on (5 minutes, max) and it will not start. Leave it for 15 minutes, and it will start right up. Checked: kill switch - disengages properly, engages properly. Kill switch wire - no bare spots, routed correctly. Air filter - clean. Fuel system clean - this mower is garage kept. Very clean. Replaced: carburetor and ignition coil. Customer took the mower home. He mowed 30 minutes, repeat problem. Help??