Hi -A friend of mine who lives in Peru has 4 ST60s which are in good working order and which he would like to keep using for a while longer. He asked to see if it possible to get piston rings for those engines here in the U.S. I have a couple of questions:1) Is it possible to get replacement rings and if so where?2) To keep the engines running would it make more sense to replace the piston, ring and liner? I am wondering if he has the right idea or if he is going to need additional parts.Thank you,TeoTeo