I'm getting back into casting bullets after several years layoff. Having a problem with my RCBS ProMelt Furnace: I have to keep heating the discharge nozzle with a torch, sometimes after filling a four cavity mould. Once the pour starts it will keep pouring till I shut it off. Then I may have a problem starting the next pour. I don't recall having to do this years before. I have the furnace set at about 740 degrees and didn't want to go much higher because of the appearance of frosting. Am I going to have to set it higher or is there something wrong with the furnace?