Quite a while ago I recall a guy who punched a hole in the top of a Stihl piston. think it was a 19x model like the budget top handle. It turned out the saw originally came with a piston stop that was supposed to be used at the edge of the piston not in the center. Stihl hides their parts sheets, so it is hard for me to know if that model has a specific piston stop. They don't hide the owners manuals but that is not current. If you have a tool to grab the clutch and an impact driver of sufficient size to drive it the inertia of the flywheel is all that is needed. Obviously must go in the correct direction first try. If the tool has the same size hex as the spark plug the scrench can be struck with a stick or similar while supported on the other end and the same result achieved. At least for an Echo 361p.