I have Stihl FS36 and it has scratched piston & cylinder and it wont start. I read here that it is the same like Ryobi or similar to MTD, if its true which models? How about spare parts prices (piston & cylinder). I think that Stihl parts will be more expensive than Ryobi. I dont want to buy new one trimmer before I try all posibilities to make the old one work.