I have a few molds that I modded that have similar issues. What I do, is heat the lead as hot as you can so it flows better. I try to put the Lee spout as close to the pour hole as I can and angle it so the lead pours straight down into the mold. Lastly, open the spout full so the lead flows as fast as it can. You may over pour a few until you get your timing down but unless you’re doing large numbers doesn’t matter. Hope that helps your problem.