While some leave lead in the pot when done I'm not one of them. My 2 original pots were 24 and 27 years old - and I finally had to go to Lee for their 1/2 price replacement program. Those pots before they died made 1000's of jigs and I love how easy they are to use. The Lee's will leak, they are a bottom pour pot and stuff sinks.
You didn't say anything about fluxing your lead!!! If you don't DO IT!!!!!!!!!!!! Until a thread about it on TackleUnderground Best Lead Melt Flux? - Wire Baits - TackleUnderground.com I had never fluxed my lead, and I'm a convert!!!!!!!!!!!!!!!! It helps keep the lead clean and makes it pour so much better.
Here's what I do for cleaning after EVERY USE!!!
When all the lead is out of the pot I WEARING GLOVES tilt it forward to get any remaining lead to flow out the hole, I turn the pot down to about 200 degrees and then I shove the jig wire (old bass jig with the barb cut off and shaped into an L) up into the hole from the bottom and remove any clogs/buildup, then I use a long piece of spinner making wire and do the same from the top.
I then turn the pot off and let it cool totally. When cooled I pull the pouring bar out of the pot and use an old knife and a piece of steel wool to get any crap off it and then use an old flat head screwdriver to scrape the inside of the pot down. I tip the pot over and knock all the scrapings out then use a big piece of steel wool to wipe the inside of the pot till totally clean. I even use a fine long handled flat head screwdriver to help clean the pour spout inside the pot, tip it over and knock anything out, put the pour bar back in and it's set to go.
It worked well for me and the pots lasted a LONG time. That the original pots lasted 24 and 27 years shows it works, plus when you go to pour again everything is clean and ready to go.