To tell the truth, I only got 3 smokes out of my last one before it opened. But I was running it wide open and non-stop to get some extra heat. Mine's in a 2" vertical pipe of gravity feed pellets so I just screwed out the 1/4NPT fitting holding the cartridge and I now fire in a propane torch to start the pellets (and replace with a 1/4 plug). I have another $5 dollar unit to replace it but haven't got around to it yet.
Thermal cycling is hard on these things too. I can believe they just don't last more than a dozen smokes. At $5, I'm willing to consider it a consumable part, especially if it fails after the smoker is started so it hasn't ruined a smoke.
Any longtime Traeger customers want to claim 100's of heat cycles without a problem? The Traeger units may be better than the eBay Chinese ones.
I wonder if you didn't have other issues with the unit that blew the fuse? Then when the thing restarted the 4-minute cycle (which sounds reasonable) things were just too hot for the little heater. Your unit looked pretty weathered initially so I'd check to make sure all insulation on motors, fans, etc are all A-ok.
I'm putting my next one in line with a 600 watt PWM light dimmer so I can run it at lower temperature and hope to get more life out of it. Of course getting the same wattage in a longer or larger diameter unit could lead to longer life too. Just don't bother with a 240 volt model. They won't get hot at all.