I have a one year old husky 365xt and the chain won't stay tight. I can tighten it and as soon as using it it loosens up. All parts on the tensioner assembly look to be fine. I've noticed that if I tighten the chain and run the chain around the bar by hand that at about half way around it loosens and if I keep moving it around it tightens and the loosens again. I'm out of ideas. I've tried numerous chains. Bar maybe?