I probably only hold the torch there for 20 or 30 seconds, but then when the flame goes out, I blow on it, down & toward the unburned pellets until the flame comes back.
Then when the flame goes out, I do the same thing again. I keep doing this again & again. Sometimes the flame is going for 5 to 8 minutes before it goes out.
Once I have a really big red cherry deep into the bottom of the pellets, it's ready to go in the smoker. This could take 20 minutes or longer, but I only spent time at the AMNPS of about 20 seconds, 6 or 8 times.
I also never use the torch again after that initial 20 to 30 seconds unless I can't get the flame back from blowing on the red pellets in the bottom.
Have you tried a hair dryer, or a inflatable mattress blower etc?