just got the new bar and chain for my XL-12 today. 18 inch Carlton pro champ, oregon lpx chain. got 66 drive links of chain like the bar says, but when i mounted it all up, i have to crank the tensioner almost all the way to get the chain even close to tight enough. there's no markings on the box as to pitch or anything like that. i told the dealer i need a loop of 66 links, .050 guage, 3/8 pitch. if he gave me the wrong pitch would it cause this? also, the sprocket is pretty well worn. could this have anything to do with it?