I bought an old blizzard 810pp plow I've replaced the main rams on it just to be safe it worked great for one day. Then it just doing everything I could hear the motor on the plow running but it wouldn't do anything. So needless to say and after taking it apart and making sure the pump wasn't broken put it back together. Now everything works but the plow will not stay in the up position. Falls as soon as I let off the controls. I replaced the main relief valve thinking it was faulty but still same effects.