I used to struggle with this too until I discovered this thing.
https://www.stihlusa.com/products/chain-saws/filing-tools/2in1file/
It is simply amazing and was way cheaper than $180. I use my saw all the time and I'm always cutting dirty wood that is tough on chains. I've had the same chain for three years now and my saw stays razor sharp.
It is a little hungry in this video because I filed the rakers low but I like it that way.
https://www.youtube.com/watch?v=TR4zIPvjHq0