I have a Husky 45 chainsaw that has been a very reliable saw for years. Recently it has gotten very hard top crank (pull). It will fire off after about 3 pulls but it is extremely difficult to pull (not normal). I removed the bar and chain - still hard. I removed the spark plug, thinking that maybe the piston was freezing up but it seems to spin very easy. It feels like the compression is stopping it from spinning?? Does anyone have any ideas??