Polaris plow not fitting

I have a 2012 Sportsman 550. I bought it ne and had the plow bracket installed at purchase. I have never had a problem until yesterday. I hook the plow up to the two pins near the winch. I then hook up my wich to the plow and raise the winch and plow. This action engages the rear lock pins, and when I hear them snap into place, I am ready to plow. Yesterday when I tried this, the two locking pins under engine would not engage. The arm from the plow that hold the locking arm seems to be a 1/2 inch short on both sides. Nothing seems bent. Any ideas