Open up the back hood above the feed rollers and look at that oval galvanized plate that connects to your forward/reverse control bar. When you move the control bar it rolls that plate up and down and it has grooves in it that flip switches for forward, neutral and reverse on a control box. Make sure one of the little tabs arent jammed or broke off. I have a 1400 and and have never had that problem but my 1000 was stuck in reverse one day and it was because one of those little switches was stuck in causing it to stay in reverse. Just had to spay it with some lube and it was good to go. Its usually something stupid that you wouldnt expect when that happens. Too much electrical junk to screw up on those machines, sensors, solenoids etc.. Let me know what the problem was incase my ever decides to do that. Good luck