I have an RCS140 that was a very good runner until I dumb thumbed into the ground. I had to replace the shaft,piston, ignition and muffler. It had little compression so I got a new ring and it fixed the compression problem. I managed to get about 15 flights out of it until I had to replace the carburator. When I was trying to get the high speed mixture adjusted ( I had been flying it too rich) it suddenly quit and refused to restart. I found the spark plug loose. I retightend the spark plug but it still refuses to start and there is very little compression. I disassembled it and could find nothing wrong but the ring seems a bit limp. I put several drops of oil in on the piston but there still seems to be little compression. Is it possible that I fried the ring? Does one go out this suddenly?