I just bought the 7 & 9 oz flutter lure mold from Do-It Molds. I am having alot of trouble getting a clean lure from it. I am pre-heating the mold, pouring fast, slow, tilting the molds, etc... and I can not figure it out!! Sometimes they'll come out clean so I'll put in a wire insert and then the next set comes out like crap. Please help!!!