My father-in-law and I were cutting wood and his Husky 55 started acting funny out of nowhere. It's never give a minutes trouble in it's 6-7 years of running. It got to where it wouldn't idle and was hard to start. Just happened to him between 2 passes through a 15" oak. I removed the top cover and immediately noticed that the spark plug was way loose- at least 1 full turn. Also, the back half of his air filter had popped loose from the front half. I tightened the plug and popped the air filter back on and got it running but it still doesn't want to idle and is hard to start. Should I simply install a new plug before I panic? I don't really see why the plug backing out would "ruin" the plug but maybe it could? Or, did he suck trash down in the carb due to the air filter being loose and toast his piston/jug? Compression still feels as good as ever but maybe I should remove the muffler and take a look... Suggestions?