ok, this problem has been going on for a while and is getting old. I have a craftsman 18.5 hp, 917.274641, thats about 7yrs old. I just replaced the battery. The tractor is hard to start, even with a new battery, even with the battery charger hooked up. The engine doesn't want to spin. Its like there isn't enough cca or there is too much tension to turn the engine. Each time I need to start, I have to hook the charger up and its stills takes several attempts to spin it. It makes a little hum, and might turn once or twice, then hums again. If I let the charger sit for a while, I can usually get it started. I just replaced the battery, even though the shop said the old battery was still good. Do I need a new starter? is napa selling me the wrong battery? Its listed as 275 cca. ideas?