I have a 2012 yard machine lawn tracter and it won't start. I have changed the selinoid and battery still won't start. It does crank sometimes but not every time. Can turn it byy hand but feels like it sticks in certin positions and won't go no farther without a lot of pressure. I'm kind of stumped please help

Hi,
Sounds like it needs a valve adjustment. You do not say whether it is a single or a twin, however there are videos on that adjustment on both on YouTube.
Single at: https://www.youtube.com/watch?v=NjzX-PUjKmo
Twin at: https://www.youtube.com/watch?v=hGkn0jR9RJM
Peace,
Clarke