Mysterious Combustion Issue

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Here we are again. I've gone through 3 exhaust blowers and now I'm on a whole new assembly from the factory. Same issue...window turning black within the hour and pellets piling up quickly, especially if turned above 3.

I hammered on the firebox with a mallet and got a ton on junk out, cleaned the vacuum port, wire brushed throughout including the exhaust and checked the OAK again, plus the installation of the new motor. I can see lots of air in the burn pot as the fire creates a fast circle around the air holes.

I've attached a photo of the professionally installed system and I think there's too many bends, but I don't know. It goes straight out the wall a few feet. The exhaust coming out the end seems to be on par with the amount the other stove with the 4" exhaust puts out, maybe a tad less.

The fire also looks the same although the other problem-free stove's always has a flame that darts around like a windy camp fire.

IMG_20231223_013415663.jpg IMG_20231223_014057448_HDR.jpg

To go over what's been done:
Exhaust taken apart and cleaned (not much in it)
Exhaust resealed thoroughly
Snake camera used to look through passages
New door gasket
Thoroughly cleaned
Used another pellet brand and type
New burn pot design
New blowers
Cleaned pressure switch assembly
Reset control board
Too much time spent adjusting control board
Reinstalled OAK
Ran without OAK

The vacuum error indicator isn't flashing again after adjusting the settings. However the issue remains! I have the feed delay at the lowest and the air rate has to match it or be lower. Why can I adjust the combustion air lower than the feed rate? I can confirm it's not a good idea.
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On your exhaust photo I don’t see a clean out tee or is it just the angle?
Well that’s part of your problem, and have you cleaned that out?
Came home today and the stove is full of pellets. I don't feel any exhaust inside and most of the smoke exits the door.

I'm wondering if an expert here can tell me if the 90 elbows are too restrictive on my setup. It goes straight out the wall a few feet.

I was going to cut out more of an opening to install a 4" vent with one 45 elbow but I don't want to go through all that if the current exhaust is acceptable. It was professionally installed. I could also swap my other stove in it's place but the exhaust is on the other side. Again, a lot of work for potentially nothing. I just cleaned and reinstalled the exhaust after it did this last week. After two years, there's honestly nothing else to look for.

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