why won't it go foward or in reverse?

I had a similar problem with my JD 855.

> Make sure that it is in gear. My daughter had bumped it into neutral.

>I have a safety gear box shut-off. A spring loaded pin under the seat that releases when you lift off of the seat. It came loose and unseated from the lever.
The tractor would not go forward or backward until I devised a short term fix that held the lever under the seat down.

>Some times the brake release has to be jiggled to get it to release properly.

Rick Evans
June 2010