Cart won't fire, drained a new battery

[krhonn]

Howdy all. Pulled the old cart out of retirement not to long ago. It needed a new starter/generator. Found one on eBay but the guy wasn't for sure what type of cart it came off of. I hooked it all up by going off of the markings that matched my old one. I also bought a new battery. After finally getting it running again the kids put an hour or so on it. They stopped and it wouldn't fire again. The motor sllloooowwwlllyyyy cranks over. I hooked some jumper cables to the battery and it fired right up. Took the cables off and nothing. Any ideas?

Thanks in advance