Gasoline tap drips right after turning off

Hello, again the (almost) “Harley newcomer”… with a problem…. At the penultimate refuelling I noticed that it drips somewhere on the gas tap, and always when the engine has run, and is turned off. The whole haunt is sometimes more powerful and sometimes less hefty and then stops again after a short time. I once raised the tank and pulled all the screws with a long screw peter, which did not bring any improvement. At the moment I push at the parking a A small metal tin underneath it so that the petrol doesn’t run over the hot engine. Depending on how strong it is, the amount that runs out at the end differs. I think so between one and another half “finger hats”…….. What could that be?? With a broken seal it would have to drip constantly??? Thank you for your help