Riding mower start issues

I had a similar problem with my John Deere rider. When I inspected the battery cables at starter and battery, they were visually clean and shiny, but I cleaned them all anyways. (Battery terminals, posts, relay connections, starter connection and ground). After that she cranked every time. If this doesn't help, get your battery tested. For some reason they only put nominal battery sizes on these things and battery life isn't usually pristine.