Progress report.
The Lee pot was not new when I got it. Since I was not getting a consistent flow when I poured, I decided to start over completely.
Yesterday I emptied the pot completely. There was a ton of crude at the bottom.
Today I removed the spout pin, and scraped all the junk out. And I got all the crap out of the spout. All that junk is now in the recycle bin.
I wound up with more than a pound of pure lead. I think its pure, but I will flux it with paraffin before I use it and add a flaming paper towel, per your advice. Evidently the previous user never fluxed his lead, and just dropped more old sinkers into the pot when his lead was low.
Once I've got clean lead to work with, I'll try again, loading my mold with hooks and Teflon pins, heating it over the pot for five minutes, and then pouring at 850+ to see how the reworked system does.
It won't be for a few days. Big rains coming tomorrow and Thurs, so I can't flux outside like I need to. Friday should be the day for fluxing and more pouring.
Fingers crossed, and thanks to everyone for all the good advice.