Did a compression test and had trouble reading the gauge when pulling the starter rope but it looked like 60 psi or more.
First you must obtain a proper small engine compression tester as a schrader valve [valve core] at the end of the hose. It will hold the compression reading after testing until it is released. Now these schrader valves are different than the ones used in tire valve stems as they a lighter spring in them.
Second this is a two cycle engine and it must have at least 100 psi compression to even start. If your reading is below this then either the compression ring is stuck or there is heavy cylinder and piston damage. First check for cylinder and piston damage by removing the muffler and looking thru the exhaust port as you cycle the engine; unless, you have an endoscope with a right angle mirror attachment. zrbf
Now Stihl units do carbon up over time due richer air/fuel so you might decarbonizing the engine using a decarbonizing fluid. Stihl dealers are suppose to carry this but around here none does. So I use some AC Delco version from the local auto parts store.
To do this you bring the piston to near top of the stroke where the exhaust port is blocked. Fill via the plug hole with the fluid and install the plug then you let the engine sit several hours. Remove the plug the spin forcing out any remaining. Then you attempt to start the engine. It will poorly at first as it burns off carbon and as it burn up the fluid that will be in the crankcase. If it was carbon stuck ring then the compression should start to improve after the first decarbonizing cycle.
