My ltx1000 riding mower will not move and cannot push it.

When started and running it dies when you let you foot off the brake. You cannot push it. I checked for locked up brakes and they are free. I have it on jackstands and the right rear wheel off while checking the brakes. I moved the neutral lever back and fort and do not feel it doing any thing. Tried it in every position and still will not work. I have been looking for a repair manual before I dive in and start taking it apart. Is there a way to check the drive while off the ground, on jackstands. When I research problem I get many answers. Belt. Seat safety switch. Brake safety switch. I ti never had any indication of a problem. Put it away and when tried to use it. That was all she wrote.