If the saw is treated with respect and kept sharp, properly tensioned and clean, there's not a huge amount you need to do other than clean the air and fuel filters occasionally and maybe check the spark plug. Most of the adjustments such as the carb are at factory presets and shouldn't be mucked about with.
BTW, a shaft locking lever sheared off my new Einhell brushcutter today, I rang Einhell UK and after providing proof of purchase they are sending a replacement part under warranty- pretty good service. They also do an affordable 50cc petrol chainsaw for £160, but I'll stick to my Stihl 261.