The leak you describe is coming from a stop mechanism adjusting screw. The stack up is: the adjusting screw, a sealing washer, a lock nut, another sealing washer, a cap nut and a cover.it sounds as if something has come loose. What you do, if you are willing to undertake the task, is pry off the round cover. It was installed by putting it over the cap nut and then staking it slightly. When this is off, try tightening the cap nut. If it moves at all, you have probably stopped the leak. Try running again before reinstalling the cover cap. If the leak is stopped, reinstall the cap at your convenience. If the leak continues, you will most likely have to replace the two sealing washers. You should try not to change the adjustment of the screw. The screw can be held in position by a screwdriver slot in its end. When breaking free the cap nut, have a wrench on the lock nur to keep the whole shebang from coming out.