Pellet trouble

Sounds like it has to be an air flow problem.  Is there a way of setting your vent to concentrate the air flow directly at your tray?  You are leaving your exhaust wide open?  You might try directing a small fan at your inlet vents and set your tray as close to the vent opening as possible.

I don't own a tray but do have two of the 6 inch perforated tubes.  I store my plastic bag of Traeger pellets in a damp barn with a dirt floor.  Have never done anything to dry the pellets before filling the tubes with them.  I concentrate my small propane torch on the pellets at the open end of the tube for 45 seconds, withdraw the torch, blow on the coals a couple times and stick the tube / tubes in my WSM with vents and exhaust wide open.  Never a problem.  They smoke for 3 & 1/2 to 4 hours every time.

I didn't see you mention what flavor of pellets you were using (ie, oak, pecan, apple, pit master blend)... there are a few flavors that have to be mixed with something else as they will not burn by themselves... what flavor were you trying ??

Your buddy got dust to work in the tube.. hhmmmm... myself, I could never keep that going.. and that was maple dust... works good in the tray ...

My last couple of smokes using the tube I've found.... Both, Pit Master's choice and Pecan.. About half way through a tube full it would start burning hotter and putting out a thicker, whiter smoke...