I just removed and replaced my deck for a good cleanup. The lift arms didn't want to stay down with the engine running. To get them down I had to start the engine and push them down with my foot, and then shut the engine off so they would stay there so I could reinstall the deck. Last time I had the deck off I am sure it wasn't like this. With the weight of the deck on them they work ok. Seems to me there must be a valve that isn't opening to relieve the hydraulic pressure to the lift cylinder. Any help?