I had HWH slide that wouldn't move out once. After troubleshooting for several hrs I found a wire had slid down and was holding one of the gray relief valves slightly open. Moved wire, solved problem. Suggest verifying all valves are in correct position as shown in attached photo. (Keep in mind that some of the relief valves are in the back, not facing outward)
Don't know if that will help, but it's a place to start.