Hi all- the problem isn't the stove most likely its the pellets. Infernos notorious for causing inconsistent operation of any stove ... That Adv 2t most popular design ever- The Enviro EF2/3, the Country/Lennox Winslow, the Avalon Astoria, The Harman Advance, HR Saranac all are based on this stove. The damper should be adjusted for about 1 inch out, the locking collar is typically set so its 1 inch when pushed up against the stove cowling.You can also bet that the chimney has a good amount of ash in the tee and liner if the interior cleanouts are full. I know you are getting the Astoria (nice stove) and doesn't really matter to you. The infernos prob got the POF switch dirty, leading to inconsistency or if you had some auger bridging for the auger not dropping in a timely manner. One more thing about some 2T's the vac sw is a positive pressure switch not negative like most present stove systems, the vac port is aft of the exh blower. Very few stoves produce amounts of heat like the Whitfields put out, The Adv 2T and Quest used POF swutches, The later series of Profile stoves used the Photo Eye as the POF. If you got it at the place mentioned, hope he didn't list it as a "new" left over stove. Good luck with the new one, sorry about the infernos........
Stovelark
Enviro EF3 pellet FS
Enviro Empress FPI AC
Enviro Kodiak 1700 FS wood