Argh!

[Al_Smith]

Everybody has a method to what best suites them .I go over the back looking down on top of the chain going right left right etc .The cutters are much the same angle and length .Of course if a cutter or two might be a tad shorter if it gets damaged that has little bearing on how it cuts .I normally use an older style Oregon file guide that has j-bolts instead of those cheap spring clamps which frankly are no good .Ocassional I use a bare file to open the gullets which will carry a bigger chip before it rocks out . 

[lxskllr]

I prefer Stihl files. I got a bunch of Pferd files online cause my old dealer charged a lot for Stihl files, and they're pretty good. 90% as good as Stihl in my estimation, but I'll go back to Stihl once I use these up. My new dealer is much more reasonable on prices. I'm guessing Stihl files are made my Vallorbe, so if you found a deal on them, you might be getting Stihl files cheaper than Stihl.

[Al_Smith]

I've got some Stihl files but more Pferd and Save Edge and a few Obergs which aren't made any more .Oregon files  might work on Oregon chain but hard Stihl chain knocks the teeth right off of them .Takes a better quality file .

[Tacotodd]

One thing is for sure, you are not going to hurt that chain by anything YOU try.😊