Larry, the loading every 40 minutes is normal for the MES, just be careful with pellets in the chip tray. There are multiple stories on here about that causeing a full on fire in the chamber, and destroying the whole unit. Masterbuilt specifically has a warning against using pellets in the chip, stating it can cause fire, which is in the users manual.
I have the 40 inch Master built, My 3rd Master built in 9 years. one was DOA and was replaced. They require constant feeding (once every 40 minutes) with new chips. I bought the AMPS and it goes out. i guess not enough air in the box. Anyway i started to use the pellets in the chip loader. that does produce quite a bit of smoke. usually use the pellets just when getting started, and wood chips afterward. the flavor is fine in everything but a pork butt or brisket. Rib roast is fine, plenty of smoke flavor. Am very interested in finding out how the external smoke box works for cold smoking.
Are you using the AMNPS (the Maze) or the AMNTS (the tube)? Depending on your elevation, they say the tube is for higher elevation and will stay lit easier in lower oxygen environments. Ive never had my tube go out ever, as long as I keep the exhaust all the way open, and I also pull the chip loader out a couple inches so it creates some in-flow that way.
I think of all the options available the Mailbox mod is the best. The MES generator (you can find in on Amazon by searching "Masterbuilt Smoker Generator") is not as good as mailbox mod IMHO, just doesn't produce as good of smoke as the AMNTS/AMNPS do.