Not too tough
I don't want to sound too condescending, but, you didn't know that your saws had fuel filters?
Changing them out is easy. Head over to your dealer and get the replacements for both. Should only be a few bucks each. Take the fuel cap off, and grab a piece of wire. Something like a scrap of house wiring will do, 12 or 14 gauge. Strip the insulation off, so it doesn't react to the fuel. You will need about an eight inch piece. Bend the last inch or two into a hook shape. Shove this hook into the tank and use it to catch the fuel line. Pull it towards the cap opening until you can grab the filter. If your saws use a clip on the line, you will need to take it off. Hold the hose in one hand, and pull the filter out. The barb on its' stem will make it a little tough. Put the new filter in its' place on the hose, and shove the whole mess back into the tank. The last Stihl I worked on had alomst zero slack in the line, so it may be a bit tight for working room.