Im assuming this was with the soup can on? on this popper Id not go much past 16mins as the taste and aroma becomes flatter if you over extend the roast. Its obvious that youre just not getting the heat up enough for 2nd crack. Was there any wind while you were roasting? This popper just hates wind. Needs to be under sheltered and away from wind. makes a huge diff. Would you say your roasts are around CS7 or CS8?