RMC
I understand your point. If we had been able to figure out how or why the machine "malfunctioned" for all three of us I suspect a cure could have been found. As I said one person knows more about PW than the factory and has been selling them for 20 plus years. He has fixed more PW than you could fit into three pickups. He did have it happen once for him and he never saw anything that he thought caused the problem. But even he agreed that there was a problem. Ghost, gremlins who knows. He went over the machine with an expert eye, and a fine tooth comb, and found nothing. Checked every thing and said that he saw nothing to explain the problem. He was the third strike.
He offered to swap for another machine he had, even though he did not sell me the machine. Top notch fellow in my book. But by that point I did not want this machine to cause any other problems. What if some person later had a gun blow up because of this fluke and was injured? You can not fix an intermittent problem sometime. Money is nice but peace of mind if priceless.
The fact that PW was willing to go over the machine twice, at my expense, did not make me happier when the problem did not go away. I have had other PW machines the worked without problems and loaded tens of thousands of shells on them. This machine was a Monday morning, hangover machine, made by a man who should have stayed home that day.
Only other possible cause that I can come up with is if you dropped a live primer into the powder. That would raise the pressure just a tad. Might happen with a MEC primer tray but not a PW. Not without an earthquake or some other major event and I think that you would remember that.