I just bought a new motor for my stretch cruiser. It lasted a week. Went far to see a friend and before I got there my bike just went neutral. Upon checking I saw that the nut that holds the sprocket for the motor side chain was off. I tightened it back and it worked for half a block. Now I keep getting worse results. I think the cam may be stripped or something but the nut goes back on so I'm not sure if that's the problem. And I have no clue how to make it work. Please help.