Thermocoupler seems to be the number one thing that goes out. Easy fix, if you have one on hand you won't miss a beat.
Even though I have never had an igniter go out on me in nearly 4 years it seems to be a distant number two.
Other than that, fairly basic machine. If your like me and buy something and do not use it for a few years, problem is finding it.
Yep, that's a great choice. You can't use it without one. If the ignitor goes out you can still ignite pellets manually, put them in the smoker and smoke on.
That said, I have a thermo and an igniter as spares. Almost 5 years in, and they are still spares, good Yoder!