Cold. Snowing. Indoor activities. I took the FS61 apart to look for damage on the inside. The cylinder liner has a few vertical lines. One of them looks serious. When I slide my fingernail over it, I can feel that there is "something" on the cylinder wall. If I put some oil on the piston, block the crankcase vent and move the piston down, I can see air coming up between the piston and liner. How did this happen, and could this be the reason for the problems?