For round ball, pot temp about 750F. You didn't mention your pot or pour method. When I'm casting 69cal RB, I run the pot at about 750F, bottom pour, put sprue back in immediately. I try to keep the pot about half full both for thermal mass and to keep a fairly consistent pour "pressure" from the nozzle. Flux when you recharge the pot. I use cedar sawdust and a small chunk of parafin.
Lee molds (and most aluminum ones) come to operating temp fast. You might benefit from some 2cycle oil lubing the sprue plate pivot point. At the risk of angering some, I'm generally not a fan of Lee molds. They are built to a price point and as such are great for new casters to get started. Once you're spent a bit of time casting and can try some RCBS, Lyman, Accurate, etc molds, you'll see the difference and why the others cost more. I currently have only one (1) Lee mold I actively use in casting. It's a flat nose "wadcutter" minie that looks like an old school trashcan. It shoots great out of my Parker Hales, but sadly, Lee has discontinued this mold. I bought a couple spares as back ups off fleebay.
If you're new to casting, there are much, much less expensive place to get lead. I have a local scrap yard that sells xray room lead at spot price. So I'm getting darn near pure lead for about $.92/lb last time I went there. Many times I can cut it into strips with no contaminants on it and go straight to the pot without having to smelt it into ingots.