Retake you a flat blade screwdriver. There is a slot in the stem you lift with the handle. Let pot get hot give 30 to 45 minutes to get good and hot. Then take screwdriver and twist that stem back and forth several times without lifting handle. You can turn it back and forth and you will feel kinda of a sweet spot where it wants to center on that wire. Then try lifting and see how it pours. Sometime that stem will get turned and hang on lift wire not letting it close. And if that still doesn’t help the pour take a paper clip and straighten it out and bend a 90 in one end about a inch and a half, holding with a pair of needle nose get it started into pour spout and while lifting handle slide it in and out to knock any debris loose and out of the way. Also remember as lead gets low the flow will also be reduced because of the lack of weight to push it out. And be careful that hot lead can do some serious damage to your hands and face.