First thing I would look at is my chain sprocket if it is worn you might want to replace it with a new 7 tooth/.325 rim sprockrt kit by Oregan off of e-bay for $14.99 + shipping. I like the rim sprocket better because the chain always rides in the same spot and therefor doesn't loosen up after you start using it.
All the best,
Will
#4
themowerking20
Look at the front of your saw at the base( power head) end of the bar opposite side of clutch Sprocket cover there should be a flat head screw that is your chain tensioner if the screw aint there go get a tensioner