I have a Poulan Pro 20" chainsaw that doesn't seem to have any power. It has a new chain but when I try to cut anything it just stops the chain. The saw isn?t more than six months old so I could get it covered under the warranty but that is such a hassle I would prefer just to fix it myself if I knew what to look at. Has anybody run into this problem before? I have tow of these saws and the other one works fine so I know it?s something with this one. Any ideas?