Calling someone to come to the house again, is going to get expensive. If the stove ran great after the last time the exhaust blower was removed, then I would like to know what the condition was of the exhaust blower and housing when they pulled it? Was it clogged, or just normal build up?
With the stove off, can you open the door and get a picture of the burn chamber? Then a close up of the burn pot,and maybe pull it out and get a picture of the cavity where the pot sits?
If it ran fine after pulling the exhaust, the issue has to be within that system. I doubt anything is in the inlet. But it is important that the holes in the burn pot be open as that is how the air comes up thru the pellets. So the cavity that the burn pot sits in has to be reasonably clean and the holes open. Even with my clean burning pellets, I have to scrape the bottom of the burn pot daily, and at every few cleanings, I have to take a drill bit to clean the carbon build up out of the holes. If the bottom holes plug, then the side holes will only feed air to the fuel load from the sides, which, IMO, will make a lazy flame and cause sensor errors etc.
To me, given the recent descriptions here, it sounds like a simply issue and should be an easy fix. Perhaps with just an adjustment in daily procedure or the like. Given that the exhaust blower was pulled and then the stove worked well, I'm betting the burn pot was pulled too and the holes opened.