I purchased 2 of the tray smokers, and in spite of following all the tips, and building a mailbox mod, They would not stay lit.
My elevation is above 5000 feet. Even when sitting on the ground, or in a grill with massive air leaks, it would not stay lit (let alone in my MES 40 with a mailbox mod).
I purchased a hot air gun, on someone's suggestion to get the coal bed massively stoked; it made no difference.
None of the classical suggestions worked. (microwave, air-flow, heat-gun, pellet type, no-water tray, placement in MES and mailbox mod).
I ran across postings from other users which were interesting.
1. Other users who were at higher altitudes were also having problems keeping their tray lit.
2. Other users were complaining the Tube smoker made too much smoke.
3. One other user, at high altitude was using the tube smoker with success.
This led me to believe the Tube smoker might be just what was needed at my altitude.
I bought 12 inch model, cured it, heated my pellets in the oven at 300 F.
Started it up with just a torch, did not stoke it with my heat gun.
Put it in my mailbox mod....
And it burned perfectly!!
When it was down to 2 inches of unburned pellets, the ashes were shaken out of it (gently, so as not to disturb the coal bed). "B" brand pellets were dumped in, on top of the existing burning pellets (these new pellets had not been toasted)....
And it burned back towards the filling hole without a hitch!
For those at higher altitudes, who cannot keep the tray burning, don't give up. Get the Tube smoker; it worked for me.