Grobet's are hard to find in my part of the country. Also I use a 5" bench vice to clamp the bar in to sharpen the chain on the saw in the shop. Tighten the chain before you start to hold the link flat against the bar before starting. Stihl has a double same side tooth and a green link to use as a start marker. I use a paint pen on my Husky's to mark the starting tooth. A linoleum knife works well to clean out the bar channel and also give the nose sprocket a shot of grease every time I flip the bar unless it is a hardnose bar
I like the linoleum knife idea. Grobet files always seem hard to find. But for gun work they are a joy to use.
