A friend of my wife just gave me a Solo 644. P&C looked good so I commenced to cleaning about 1/2 pound of gunk from the inner reaches of the saw. Saw starts and runs OK. I had to dress the bar rails and decided to paint it as well. the back end of the clutch cover is broken out and I need a new rim sprocket. This has .325 chain and rim sprocket is .325 8 tooth. Is that too high for this saw? I was surprised it was not a 7 tooth.